diff --git a/src/GitHub.App/Caches/AutoCompleteSourceCache.cs b/src/GitHub.App/Caches/AutoCompleteSourceCache.cs
deleted file mode 100644
index 543ceef1b7..0000000000
--- a/src/GitHub.App/Caches/AutoCompleteSourceCache.cs
+++ /dev/null
@@ -1,147 +0,0 @@
-using System;
-using System.Collections.Generic;
-using System.Diagnostics;
-using System.Globalization;
-using System.Reactive.Linq;
-using System.Reactive.Subjects;
-using GitHub.Api;
-using GitHub.Extensions;
-using GitHub.Helpers;
-using GitHub.Models;
-using GitHub.Services;
-using ReactiveUI;
-
-namespace GitHub.Cache
-{
-    public abstract class AutoCompleteSourceCache : IAutoCompleteSourceCache
-    {
-        static readonly NLog.Logger log = NLog.LogManager.GetCurrentClassLogger();
-        
-        readonly SerializedObservableProvider<IRepositoryModel, IReadOnlyList<SuggestionItem>> serializedSuggestions;
-        readonly TimeSpan cacheDuration;
-        readonly TimeSpan maxCacheDuration;
-
-        protected AutoCompleteSourceCache(TimeSpan cacheDuration, TimeSpan maxCacheDuration)
-        {
-            this.cacheDuration = cacheDuration;
-            this.maxCacheDuration = maxCacheDuration;
-
-            serializedSuggestions = new SerializedObservableProvider<IRepositoryModel, IReadOnlyList<SuggestionItem>>(
-                GetAndFetchCachedSourceItemsImpl);
-        }
-
-        // We append this to the cache key to differentiate the various auto completion caches.
-        protected abstract string CacheSuffix { get; }
-
-        /// <summary>
-        /// Retrieves suggestions from the cache for the specified repository. If not there, it makes an API
-        /// call to  retrieve them.
-        /// </summary>
-        /// <param name="repository">The repository that contains the suggestion items.</param>
-        /// <returns>An observable containing a readonly list of auto complete suggestions</returns>
-        public IObservable<IReadOnlyList<SuggestionItem>> RetrieveSuggestions(IRepositoryModel repository)
-        {
-            Guard.ArgumentNotNull(repository, "repository");
-
-            return serializedSuggestions.Get(repository);
-        }
-
-        /// <summary>
-        /// Calls the API to fetch mentionables, issues, or whatever.
-        /// </summary>
-        /// <param name="existingCachedItems">Existing items in the cache. Useful for incremental cache updates</param>
-        /// <param name="repository">The repository containing the items to fetch</param>
-        /// <param name="apiClient">The API client to use to make the request</param>
-        protected abstract IObservable<SuggestionItem> FetchSuggestionsSourceItems(
-            CachedData<List<SuggestionItem>> existingCachedItems,
-            IRepositoryModel repository,
-            IApiClient apiClient);
-
-        IObservable<List<SuggestionItem>> GetAndFetchExistingCachedSourceItems(
-            IHostCache hostCache,
-            IRepositoryModel repository,
-            Func<IRepositoryModel, CachedData<List<SuggestionItem>>, IObservable<List<SuggestionItem>>> fetchFunc)
-        {
-            Debug.Assert(repository != null, "Repository cannot be null because we validated it at the callsite");
-            Debug.Assert(hostCache != null, "HostCache cannot be null because we validated it at the callsite");
-
-            return GetOrFetchCachedItems(hostCache, repository, fetchFunc);
-        }
-
-        IObservable<IReadOnlyList<SuggestionItem>> GetAndFetchCachedSourceItemsImpl(IRepositoryModel repository)
-        {
-            Debug.Assert(repository != null, "Repository cannot be null because we validated it at the callsite");
-            
-            return Observable.Defer(() =>
-            {
-                var hostCache = repository.RepositoryHost != null
-                    ? repository.RepositoryHost.Cache
-                    : null;
-
-                if (hostCache == null)
-                {
-                    return Observable.Empty<IReadOnlyList<SuggestionItem>>();
-                }
-
-                var ret = new ReplaySubject<List<SuggestionItem>>(1);
-
-                GetAndFetchExistingCachedSourceItems(hostCache, repository, GetCacheableSuggestions)
-                    .Catch<List<SuggestionItem>, Exception>(_ => Observable.Return(new List<SuggestionItem>()))
-                    .Multicast(ret)
-                    .PermaRef();
-
-                // If GetAndFetchExistingCachedSourceItems finds that the cache item is stale it produces the
-                // stale value and then fetches and produces a fresh one. It can thus produce
-                // 1, 2 or no values (if cache miss and fetch fails). While I'd ideally want
-                // to expose that through this method so that the suggestions list in the UI get updated
-                // as soon as we have a fresh value this method has historically only produced
-                // one value so in an effort to reduce scope I'm keeping it that way. We
-                // unfortunately still need to maintain the subscription to GetAndRefresh though
-                // so that we don't cancel the refresh as soon as we get the stale object.
-                return ret.Take(1);
-            });
-        }
-
-        IObservable<List<SuggestionItem>> GetCacheableSuggestions(
-            IRepositoryModel repository,
-            CachedData<List<SuggestionItem>> existingCachedItems)
-        {
-            Debug.Assert(repository != null, "Repository cannot be null because we validated it at the callsite");
-
-            var apiClient = repository.RepositoryHost != null ? repository.RepositoryHost.ApiClient : null;
-            if (apiClient == null)
-            {
-                return Observable.Empty<List<SuggestionItem>>();
-            }
-
-            // Our current serializer can't handle deserializing IReadOnlyList<T>. That's why we need a concrete list
-            // here.
-            return FetchSuggestionsSourceItems(existingCachedItems, repository, apiClient)
-                .ToConcreteList();
-        }
-
-        IObservable<List<T>> GetOrFetchCachedItems<T>(
-            IHostCache hostCache,
-            IRepositoryModel repositoryModel,
-            Func<IRepositoryModel, CachedData<List<T>>, IObservable<List<T>>> fetchFunc)
-            where T : class
-        {
-            Ensure.ArgumentNotNull(repositoryModel, "repositoryModel");
-            Ensure.ArgumentNotNull(fetchFunc, "fetchFunc");
-
-            string cacheKey = repositoryModel.NameWithOwner + ":" + CacheSuffix;
-            return hostCache.LocalMachine.GetCachedValueThenFetchForNextTime<List<T>>(
-                cacheKey,
-                cacheData => fetchFunc(repositoryModel, cacheData),
-                cacheDuration,
-                maxCacheDuration)
-                .Catch<List<T>, Exception>(ex =>
-                {
-                    log.Info(String.Format(CultureInfo.InvariantCulture,
-                        "Exception occurred attempting to get a cached value and then fetch '{0}'", cacheKey), ex);
-                    return Observable.Return(new List<T>());
-                })
-                .Select(result => result ?? new List<T>());
-        }
-    }
-}
diff --git a/src/GitHub.App/Caches/IAutoCompleteSourceCache.cs b/src/GitHub.App/Caches/IAutoCompleteSourceCache.cs
deleted file mode 100644
index ad50aa00ef..0000000000
--- a/src/GitHub.App/Caches/IAutoCompleteSourceCache.cs
+++ /dev/null
@@ -1,17 +0,0 @@
-using System;
-using System.Collections.Generic;
-using GitHub.Models;
-
-namespace GitHub.Cache
-{
-    public interface IAutoCompleteSourceCache
-    {
-        /// <summary>
-        /// Retrieves suggestions from the cache for the specified repository. If not there, it makes an API
-        /// call to  retrieve them.
-        /// </summary>
-        /// <param name="repositoryModel">The repository that contains the users</param>
-        /// <returns>An observable containing a readonly list of issue suggestions</returns>
-        IObservable<IReadOnlyList<SuggestionItem>> RetrieveSuggestions(IRepositoryModel repositoryModel);
-    }
-}
diff --git a/src/GitHub.App/Caches/IIssuesCache.cs b/src/GitHub.App/Caches/IIssuesCache.cs
deleted file mode 100644
index d99bcc64e9..0000000000
--- a/src/GitHub.App/Caches/IIssuesCache.cs
+++ /dev/null
@@ -1,12 +0,0 @@
-using System.Diagnostics.CodeAnalysis;
-namespace GitHub.Cache
-{
-    /// <summary>
-    /// Used to cache and supply #issues in the autocomplete control.
-    /// </summary>
-    [SuppressMessage("Microsoft.Design", "CA1040:AvoidEmptyInterfaces",
-        Justification = "Yeah, it's empty, but it makes it easy to import the correct one.")]
-    public interface IIssuesCache : IAutoCompleteSourceCache
-    {
-    }
-}
\ No newline at end of file
diff --git a/src/GitHub.App/Caches/IMentionsCache.cs b/src/GitHub.App/Caches/IMentionsCache.cs
deleted file mode 100644
index b0ef8a0391..0000000000
--- a/src/GitHub.App/Caches/IMentionsCache.cs
+++ /dev/null
@@ -1,14 +0,0 @@
-using System.Diagnostics.CodeAnalysis;
-using GitHub.Cache;
-
-namespace GitHub.Helpers
-{
-    /// <summary>
-    /// Used to cache and supply @mentions in the autocomplete control.
-    /// </summary>
-    [SuppressMessage("Microsoft.Design", "CA1040:AvoidEmptyInterfaces",
-        Justification = "Yeah, it's empty, but it makes it easy to import the correct one.")]
-    public interface IMentionsCache : IAutoCompleteSourceCache
-    {
-    }
-}
\ No newline at end of file
diff --git a/src/GitHub.App/Caches/IssuesCache.cs b/src/GitHub.App/Caches/IssuesCache.cs
deleted file mode 100644
index 96dd3407e9..0000000000
--- a/src/GitHub.App/Caches/IssuesCache.cs
+++ /dev/null
@@ -1,80 +0,0 @@
-using System;
-using System.Collections.Generic;
-using System.ComponentModel.Composition;
-using System.Linq;
-using System.Reactive.Linq;
-using GitHub.Api;
-using GitHub.Extensions;
-using GitHub.Models;
-using GitHub.ViewModels;
-using Octokit;
-
-namespace GitHub.Cache
-{
-    [Export(typeof(IIssuesCache))]
-    [Export(typeof(IAutoCompleteSourceCache))]
-    [PartCreationPolicy(CreationPolicy.Shared)]
-    public class IssuesCache : AutoCompleteSourceCache, IIssuesCache
-    {
-        // Just needs to be some value before GitHub stored its first issue.
-        static readonly DateTimeOffset lowerBound = new DateTimeOffset(2000, 1, 1, 12, 0, 0, TimeSpan.FromSeconds(0));
-
-        [ImportingConstructor]
-        public IssuesCache() : base(TimeSpan.FromSeconds(10), TimeSpan.FromDays(7))
-        {
-        }
-
-        protected override string CacheSuffix
-        {
-            get { return "issues"; }
-        }
-
-        protected override IObservable<SuggestionItem> FetchSuggestionsSourceItems(
-            CachedData<List<SuggestionItem>> existingCachedItems,
-            IRepositoryModel repository,
-            IApiClient apiClient)
-        {
-            var data = (existingCachedItems.Data ?? new List<SuggestionItem>())
-                .Where(item => !String.IsNullOrEmpty(item.Name)) // Helps handle cache corruption
-                .ToList();
-
-            if (data.IsEmpty())
-            {
-                return apiClient.GetIssuesForRepository(repository.Owner, repository.Name)
-                    .Select(ConvertToSuggestionItem);
-            }
-
-            // Update cache with changes
-            var since = data.Max(issue => issue.LastModifiedDate ?? lowerBound).ToUniversalTime();
-            var existingIssues = data.ToDictionary(i => i.Name, i => i);
-            return apiClient.GetIssuesChangedSince(repository.Owner, repository.Name, since)
-                .WhereNotNull()
-                .Do(issue =>
-                {
-                    var suggestionItem = ConvertToSuggestionItem(issue);    
-                    // Remove closed ones.
-                    if (issue.State == ItemState.Closed)
-                    {
-                        existingIssues.Remove(suggestionItem.Name);
-                    }
-                    else
-                    {
-                        // Adds new ones (this is basically a noop for existing ones)
-                        existingIssues[suggestionItem.Name] = suggestionItem;
-                    }
-                })
-                .ToList() // We always want to return existing issues.
-                .SelectMany(_ => existingIssues.Values.ToObservable());
-        }
-
-        static SuggestionItem ConvertToSuggestionItem(Issue issue)
-        {
-            return new SuggestionItem("#" + issue.Number, issue.Title)
-            {
-                // Just in case CreatedAt isn't set, we'll use UTCNow.
-                LastModifiedDate = issue.UpdatedAt
-                    ?? (issue.CreatedAt == DateTimeOffset.MinValue ? DateTimeOffset.UtcNow : issue.CreatedAt)
-            };
-        }
-    }
-}
diff --git a/src/GitHub.App/Caches/MentionsCache.cs b/src/GitHub.App/Caches/MentionsCache.cs
deleted file mode 100644
index 1c2872bae6..0000000000
--- a/src/GitHub.App/Caches/MentionsCache.cs
+++ /dev/null
@@ -1,50 +0,0 @@
-using System;
-using System.Collections.Generic;
-using System.ComponentModel.Composition;
-using System.Reactive.Linq;
-using GitHub.Api;
-using GitHub.Helpers;
-using GitHub.Models;
-using Octokit;
-
-namespace GitHub.Cache
-{
-    /// <summary>
-    /// Used to cache and supply @mentions in the autocomplete control.
-    /// </summary>
-    [Export(typeof(IMentionsCache))]
-    [Export(typeof(IAutoCompleteSourceCache))]
-    [PartCreationPolicy(CreationPolicy.Shared)]
-    public class MentionsCache :  AutoCompleteSourceCache, IMentionsCache
-    {
-        public MentionsCache() : base(TimeSpan.FromHours(12), TimeSpan.FromDays(7))
-        {
-        }
-
-        protected override string CacheSuffix
-        {
-            get { return "mentions"; }
-        }
-
-        protected override IObservable<SuggestionItem> FetchSuggestionsSourceItems(
-            CachedData<List<SuggestionItem>> existingCachedItems,
-            IRepositoryModel repository,
-            IApiClient apiClient)
-        {
-            return apiClient.GetMentionables(repository.Owner, repository.Name)
-                .Select(ConvertToSuggestionItem);
-        }
-
-        static SuggestionItem ConvertToSuggestionItem(AccountMention sourceItem)
-        {
-            return new SuggestionItem(sourceItem.Login, sourceItem.Name ?? "(unknown)", GetUrlSafe(sourceItem.AvatarUrl));
-        }
-
-        static Uri GetUrlSafe(string url)
-        {
-            Uri uri;
-            Uri.TryCreate(url, UriKind.Absolute, out uri);
-            return uri;
-        }
-    }
-}
diff --git a/src/GitHub.App/Models/SuggestionItem.cs b/src/GitHub.App/Models/SuggestionItem.cs
index 0b8bd59644..713e0357e9 100644
--- a/src/GitHub.App/Models/SuggestionItem.cs
+++ b/src/GitHub.App/Models/SuggestionItem.cs
@@ -1,4 +1,5 @@
 using System;
+using GitHub.Extensions;
 using GitHub.Helpers;
 
 namespace GitHub.Models
@@ -9,36 +10,22 @@ namespace GitHub.Models
     /// </summary>
     public class SuggestionItem
     {
-        public SuggestionItem() // So this can be deserialized from cache
-        {
-        }
-
-        public SuggestionItem(string name, Uri iconCacheKey)
-        {
-            Ensure.ArgumentNotNullOrEmptyString(name, "name");
-            Ensure.ArgumentNotNull(iconCacheKey, "iconCacheKey");
-            
-            Name = name;
-            IconKey = iconCacheKey;
-        }
-
         public SuggestionItem(string name, string description)
         {
-            Ensure.ArgumentNotNullOrEmptyString(name, "name");
-            Ensure.ArgumentNotNullOrEmptyString(description, "description");
+            Guard.ArgumentNotEmptyString(name, "name");
+            Guard.ArgumentNotEmptyString(description, "description");
 
             Name = name;
             Description = description;
         }
 
-        public SuggestionItem(string name, string description, Uri iconCacheKey)
+        public SuggestionItem(string name, string description, string imageUrl)
         {
-            Ensure.ArgumentNotNullOrEmptyString(name, "name");
-            Ensure.ArgumentNotNull(iconCacheKey, "iconCacheKey");
+            Guard.ArgumentNotEmptyString(name, "name");
 
             Name = name;
             Description = description;
-            IconKey = iconCacheKey;
+            ImageUrl = imageUrl;
         }
 
         /// <summary>
@@ -52,9 +39,9 @@ public SuggestionItem(string name, string description, Uri iconCacheKey)
         public string Description { get; set; }
 
         /// <summary>
-        /// A key to lookup when displaying the icon for this entry
+        /// An image url for this entry
         /// </summary>
-        public Uri IconKey { get; set; }
+        public string ImageUrl { get; set; }
 
         /// <summary>
         /// The date this suggestion was last modified according to the API.
diff --git a/src/GitHub.App/SampleData/CommentViewModelDesigner.cs b/src/GitHub.App/SampleData/CommentViewModelDesigner.cs
index b060088de9..132fe03568 100644
--- a/src/GitHub.App/SampleData/CommentViewModelDesigner.cs
+++ b/src/GitHub.App/SampleData/CommentViewModelDesigner.cs
@@ -3,6 +3,7 @@
 using System.Reactive;
 using System.Threading.Tasks;
 using GitHub.Models;
+using GitHub.Services;
 using GitHub.ViewModels;
 using ReactiveUI;
 
@@ -37,6 +38,7 @@ public CommentViewModelDesigner()
         public ReactiveCommand<Unit, Unit> CommitEdit { get; }
         public ReactiveCommand<Unit, Unit> OpenOnGitHub { get; } = ReactiveCommand.Create(() => { });
         public ReactiveCommand<Unit, Unit> Delete { get; }
+        public IAutoCompleteAdvisor AutoCompleteAdvisor { get; }
 
         public Task InitializeAsync(ICommentThreadViewModel thread, ActorModel currentUser, CommentModel comment, CommentEditState state)
         {
diff --git a/src/GitHub.App/SampleData/PullRequestCreationViewModelDesigner.cs b/src/GitHub.App/SampleData/PullRequestCreationViewModelDesigner.cs
index 32922438d8..77edc7ab89 100644
--- a/src/GitHub.App/SampleData/PullRequestCreationViewModelDesigner.cs
+++ b/src/GitHub.App/SampleData/PullRequestCreationViewModelDesigner.cs
@@ -4,6 +4,7 @@
 using System.Reactive;
 using System.Threading.Tasks;
 using GitHub.Models;
+using GitHub.Services;
 using GitHub.Validation;
 using GitHub.ViewModels.GitHubPane;
 using ReactiveUI;
@@ -53,6 +54,7 @@ public PullRequestCreationViewModelDesigner()
         public string PRTitle { get; set; }
 
         public ReactivePropertyValidator TitleValidator { get; }
+        public IAutoCompleteAdvisor AutoCompleteAdvisor { get; }
 
         public ReactivePropertyValidator BranchValidator { get; }
 
diff --git a/src/GitHub.App/SampleData/PullRequestReviewAuthoringViewModelDesigner.cs b/src/GitHub.App/SampleData/PullRequestReviewAuthoringViewModelDesigner.cs
index cfc8eb23e4..9d0c118cbb 100644
--- a/src/GitHub.App/SampleData/PullRequestReviewAuthoringViewModelDesigner.cs
+++ b/src/GitHub.App/SampleData/PullRequestReviewAuthoringViewModelDesigner.cs
@@ -3,6 +3,7 @@
 using System.Reactive;
 using System.Threading.Tasks;
 using GitHub.Models;
+using GitHub.Services;
 using GitHub.ViewModels.GitHubPane;
 using ReactiveUI;
 
@@ -53,6 +54,7 @@ public PullRequestReviewAuthoringViewModelDesigner()
         public ReactiveCommand<Unit, Unit> Comment { get; }
         public ReactiveCommand<Unit, Unit> RequestChanges { get; }
         public ReactiveCommand<Unit, Unit> Cancel { get; }
+        public IAutoCompleteAdvisor AutoCompleteAdvisor { get; }
 
         public Task InitializeAsync(
             LocalRepositoryModel localRepository,
diff --git a/src/GitHub.App/Services/AutoCompleteAdvisor.cs b/src/GitHub.App/Services/AutoCompleteAdvisor.cs
index c1d610526c..569a87b526 100644
--- a/src/GitHub.App/Services/AutoCompleteAdvisor.cs
+++ b/src/GitHub.App/Services/AutoCompleteAdvisor.cs
@@ -7,8 +7,10 @@
 using System.Globalization;
 using System.Linq;
 using System.Reactive.Linq;
-using GitHub.UI;
-using NLog;
+using GitHub.Extensions;
+using GitHub.Logging;
+using GitHub.Models;
+using Serilog;
 
 namespace GitHub.Services
 {
@@ -18,11 +20,11 @@ public class AutoCompleteAdvisor : IAutoCompleteAdvisor
     {
         const int SuggestionCount = 5; // The number of suggestions we'll provide. github.com does 5.
 
-        static readonly Logger log = LogManager.GetCurrentClassLogger();
+        static readonly ILogger log = LogManager.ForContext<AutoCompleteAdvisor>();
         readonly Lazy<Dictionary<string, IAutoCompleteSource>> prefixSourceMap;
 
         [ImportingConstructor]
-        public AutoCompleteAdvisor([ImportMany]IEnumerable<IAutoCompleteSource> autocompleteSources)
+        public AutoCompleteAdvisor([ImportMany(typeof(IAutoCompleteSource))]IEnumerable<IAutoCompleteSource> autocompleteSources)
         {
             prefixSourceMap = new Lazy<Dictionary<string, IAutoCompleteSource>>(
                 () => autocompleteSources.ToDictionary(s => s.Prefix, s => s));
@@ -30,7 +32,7 @@ public AutoCompleteAdvisor([ImportMany]IEnumerable<IAutoCompleteSource> autocomp
 
         public IObservable<AutoCompleteResult> GetAutoCompletionSuggestions(string text, int caretPosition)
         {
-            Ensure.ArgumentNotNull("text", text);
+            Guard.ArgumentNotNull("text", text);
 
             if (caretPosition < 0 || caretPosition > text.Length)
             {
@@ -73,7 +75,7 @@ public IObservable<AutoCompleteResult> GetAutoCompletionSuggestions(string text,
                     new ReadOnlyCollection<AutoCompleteSuggestion>(suggestions)))
                 .Catch<AutoCompleteResult, Exception>(e =>
                 {
-                    log.Info(e);
+                    log.Error(e, "Error Getting AutoCompleteResult");
                     return Observable.Return(AutoCompleteResult.Empty);
                 });
         }
@@ -82,8 +84,8 @@ public IObservable<AutoCompleteResult> GetAutoCompletionSuggestions(string text,
             , Justification = "We ensure the argument is greater than -1 so it can't overflow")]
         public static AutoCompletionToken ParseAutoCompletionToken(string text, int caretPosition, string triggerPrefix)
         {
-            Ensure.ArgumentNotNull("text", text);
-            Ensure.ArgumentInRange(caretPosition, 0, text.Length, "caretPosition");
+            Guard.ArgumentNotNull("text", text);
+            Guard.ArgumentInRange(caretPosition, 0, text.Length, "caretPosition");
             if (caretPosition == 0 || text.Length == 0) return null;
 
             // :th     : 1
@@ -103,8 +105,8 @@ public class AutoCompletionToken
     {
         public AutoCompletionToken(string searchPrefix, int offset)
         {
-            Ensure.ArgumentNotNull(searchPrefix, "searchPrefix");
-            Ensure.ArgumentNonNegative(offset, "offset");
+            Guard.ArgumentNotNull(searchPrefix, "searchPrefix");
+            Guard.ArgumentNonNegative(offset, "offset");
 
             SearchSearchPrefix = searchPrefix;
             Offset = offset;
diff --git a/src/GitHub.App/Services/EmojiAutoCompleteSource.cs b/src/GitHub.App/Services/EmojiAutoCompleteSource.cs
deleted file mode 100644
index 73c9f2780c..0000000000
--- a/src/GitHub.App/Services/EmojiAutoCompleteSource.cs
+++ /dev/null
@@ -1,41 +0,0 @@
-using System;
-using System.ComponentModel.Composition;
-using System.Linq;
-using System.Reactive.Linq;
-using System.Windows.Media.Imaging;
-using GitHub.UI;
-
-namespace GitHub.Services
-{
-    [Export(typeof(IAutoCompleteSource))]
-    [PartCreationPolicy(CreationPolicy.Shared)]
-    public class EmojiAutoCompleteSource : IAutoCompleteSource
-    {
-        readonly IEmojiCache emojiCache;
-
-        [ImportingConstructor]
-        public EmojiAutoCompleteSource(IEmojiCache emojiCache)
-        {
-            Ensure.ArgumentNotNull(emojiCache, "emojiCache");
-
-            this.emojiCache = emojiCache;
-        }
-
-        public IObservable<AutoCompleteSuggestion> GetSuggestions()
-        {
-            Func<Uri, IObservable<BitmapSource>> resolveImage = uri =>
-                Observable.Defer(() =>
-                {
-                    var resourcePath = "pack://application:,,,/GitHub;component/" + uri;
-                    return Observable.Return(App.CreateBitmapImage(resourcePath));
-                });
-
-            return emojiCache.GetEmojis()
-                .Where(emoji => !String.IsNullOrEmpty(emoji.Name)) // Just being extra cautious.
-                .Select(emoji => new AutoCompleteSuggestion(emoji.Name, resolveImage(emoji.IconKey), ":", ":"))
-                .ToObservable();
-        }
-
-        public string Prefix { get { return ":"; } }
-    }
-}
diff --git a/src/GitHub.App/Services/IAutoCompleteSource.cs b/src/GitHub.App/Services/IAutoCompleteSource.cs
index 0aea7bf1a7..09b77c4cc3 100644
--- a/src/GitHub.App/Services/IAutoCompleteSource.cs
+++ b/src/GitHub.App/Services/IAutoCompleteSource.cs
@@ -1,6 +1,5 @@
 using System;
 using GitHub.Models;
-using GitHub.UI;
 
 namespace GitHub.Services
 {
diff --git a/src/GitHub.App/Services/IssuesAutoCompleteSource.cs b/src/GitHub.App/Services/IssuesAutoCompleteSource.cs
index 1ceca2a1d2..d2c64e671c 100644
--- a/src/GitHub.App/Services/IssuesAutoCompleteSource.cs
+++ b/src/GitHub.App/Services/IssuesAutoCompleteSource.cs
@@ -3,10 +3,13 @@
 using System.ComponentModel.Composition;
 using System.Linq;
 using System.Reactive.Linq;
-using GitHub.Cache;
+using GitHub.Api;
+using GitHub.Extensions;
 using GitHub.Models;
-using GitHub.UI;
-using GitHub.ViewModels;
+using GitHub.Primitives;
+using Octokit.GraphQL;
+using Octokit.GraphQL.Model;
+using static Octokit.GraphQL.Variable;
 
 namespace GitHub.Services
 {
@@ -14,33 +17,80 @@ namespace GitHub.Services
     [PartCreationPolicy(CreationPolicy.Shared)]
     public class IssuesAutoCompleteSource : IAutoCompleteSource
     {
-        readonly Lazy<IIssuesCache> issuesCache;
-        readonly Lazy<ISourceListViewModel> currentRepositoryState;
+        readonly ITeamExplorerContext teamExplorerContext;
+        readonly IGraphQLClientFactory graphqlFactory;
+        ICompiledQuery<Page<SuggestionItem>> query;
 
         [ImportingConstructor]
-        public IssuesAutoCompleteSource(
-            Lazy<IIssuesCache> issuesCache,
-            Lazy<ISourceListViewModel> currentRepositoryState)
+        public IssuesAutoCompleteSource(ITeamExplorerContext teamExplorerContext, IGraphQLClientFactory graphqlFactory)
         {
-            Ensure.ArgumentNotNull(issuesCache, "issuesCache");
-            Ensure.ArgumentNotNull(currentRepositoryState, "currentRepositoryState");
+            Guard.ArgumentNotNull(teamExplorerContext, nameof(teamExplorerContext));
+            Guard.ArgumentNotNull(graphqlFactory, nameof(graphqlFactory));
 
-            this.issuesCache = issuesCache;
-            this.currentRepositoryState = currentRepositoryState;
+            this.teamExplorerContext = teamExplorerContext;
+            this.graphqlFactory = graphqlFactory;
         }
 
         public IObservable<AutoCompleteSuggestion> GetSuggestions()
         {
-            if (CurrentRepository.RepositoryHost == null)
+            var localRepositoryModel = teamExplorerContext.ActiveRepository;
+
+            var hostAddress = HostAddress.Create(localRepositoryModel.CloneUrl.Host);
+            var owner = localRepositoryModel.Owner;
+            var name = localRepositoryModel.Name;
+
+            string filter;
+            string after;
+
+            if (query == null)
             {
-                return Observable.Empty<AutoCompleteSuggestion>();
+               query = new Query().Search(query: Var(nameof(filter)), SearchType.Issue, 100, after: Var(nameof(after)))
+                       .Select(item => new Page<SuggestionItem>
+                       {
+                           Items = item.Nodes.Select(searchResultItem => 
+                               searchResultItem.Switch<SuggestionItem>(selector => selector
+                                       .Issue(i => new SuggestionItem("#" + i.Number, i.Title) { LastModifiedDate = i.LastEditedAt })
+                                       .PullRequest(p => new SuggestionItem("#" + p.Number, p.Title) { LastModifiedDate = p.LastEditedAt }))
+                               ).ToList(),
+                           EndCursor = item.PageInfo.EndCursor,
+                           HasNextPage = item.PageInfo.HasNextPage,
+                           TotalCount = item.IssueCount
+                       })
+                       .Compile();
             }
 
-            return IssuesCache.RetrieveSuggestions(CurrentRepository)
-                .Catch<IReadOnlyList<SuggestionItem>, Exception>(_ => Observable.Empty<IReadOnlyList<SuggestionItem>>())
-                .SelectMany(x => x.ToObservable())
-                .Where(suggestion => !String.IsNullOrEmpty(suggestion.Name)) // Just being extra cautious
-                .Select(suggestion => new IssueAutoCompleteSuggestion(suggestion, Prefix));
+            filter = $"repo:{owner}/{name}";
+
+            return Observable.FromAsync(async () =>
+            {
+                var results = new List<SuggestionItem>();
+
+                var variables = new Dictionary<string, object>
+                {
+                    {nameof(filter), filter },
+                };
+
+                var connection = await graphqlFactory.CreateConnection(hostAddress);
+                var searchResults = await connection.Run(query, variables);
+
+                results.AddRange(searchResults.Items);
+
+                while (searchResults.HasNextPage)
+                {
+                    variables[nameof(after)] = searchResults.EndCursor;
+                    searchResults = await connection.Run(query, variables);
+
+                    results.AddRange(searchResults.Items);
+                }
+
+                return results.Select(item => new IssueAutoCompleteSuggestion(item, Prefix));
+
+            }).SelectMany(observable => observable);
+        }
+
+        class SearchResult
+        {
+            public SuggestionItem SuggestionItem { get; set; }
         }
 
         public string Prefix
@@ -48,10 +98,6 @@ public string Prefix
             get { return "#"; }
         }
 
-        IIssuesCache IssuesCache { get { return issuesCache.Value; } }
-
-        IRepositoryModel CurrentRepository { get { return currentRepositoryState.Value.SelectedRepository; } }
-
         class IssueAutoCompleteSuggestion : AutoCompleteSuggestion
         {
             // Just needs to be some value before GitHub stored its first issue.
diff --git a/src/GitHub.App/Services/MentionsAutoCompleteSource.cs b/src/GitHub.App/Services/MentionsAutoCompleteSource.cs
index e90c0b0d9b..68fc002292 100644
--- a/src/GitHub.App/Services/MentionsAutoCompleteSource.cs
+++ b/src/GitHub.App/Services/MentionsAutoCompleteSource.cs
@@ -1,15 +1,15 @@
 using System;
 using System.Collections.Generic;
 using System.ComponentModel.Composition;
+using System.Linq;
 using System.Reactive.Linq;
 using System.Windows.Media.Imaging;
-using GitHub.Caches;
+using GitHub.Api;
 using GitHub.Extensions;
-using GitHub.Helpers;
 using GitHub.Models;
-using GitHub.Services;
-using GitHub.UI;
-using GitHub.ViewModels;
+using GitHub.Primitives;
+using Octokit.GraphQL;
+using static Octokit.GraphQL.Variable;
 
 namespace GitHub.Services
 {
@@ -20,58 +20,77 @@ namespace GitHub.Services
     [PartCreationPolicy(CreationPolicy.Shared)]
     public class MentionsAutoCompleteSource : IAutoCompleteSource
     {
-        readonly Lazy<IMentionsCache> mentionsCache;
-        readonly Lazy<ISourceListViewModel> currentRepositoryState;
-        readonly Lazy<IImageCache> imageCache;
-        readonly IAvatarProvider hostAvatarProvider;
+        const string DefaultAvatar = "pack://application:,,,/GitHub.App;component/Images/default_user_avatar.png";
+
+        readonly ITeamExplorerContext teamExplorerContext;
+        readonly IGraphQLClientFactory graphqlFactory;
+        readonly IAvatarProvider avatarProvider;
+        ICompiledQuery<List<SuggestionItem>> query;
 
         [ImportingConstructor]
         public MentionsAutoCompleteSource(
-            Lazy<IMentionsCache> mentionsCache,
-            Lazy<IImageCache> imageCache,
-            IAvatarProvider hostAvatarProvider)
+            ITeamExplorerContext teamExplorerContext, 
+            IGraphQLClientFactory graphqlFactory,
+            IAvatarProvider avatarProvider)
         {
-            Guard.ArgumentNotNull(mentionsCache, "mentionsCache");
-            Guard.ArgumentNotNull(currentRepositoryState, "currentRepositoryState");
-            Guard.ArgumentNotNull(imageCache, "imageCache");
-            Guard.ArgumentNotNull(hostAvatarProvider, "hostAvatarProvider");
+            Guard.ArgumentNotNull(teamExplorerContext, nameof(teamExplorerContext));
+            Guard.ArgumentNotNull(graphqlFactory, nameof(graphqlFactory));
+            Guard.ArgumentNotNull(avatarProvider, nameof(avatarProvider));
 
-            this.mentionsCache = mentionsCache;
-            this.currentRepositoryState = currentRepositoryState;
-            this.imageCache = imageCache;
-            this.hostAvatarProvider = hostAvatarProvider;
+            this.teamExplorerContext = teamExplorerContext;
+            this.graphqlFactory = graphqlFactory;
+            this.avatarProvider = avatarProvider;
         }
 
         public IObservable<AutoCompleteSuggestion> GetSuggestions()
         {
-            if (CurrentRepository.RepositoryHost == null)
+            var localRepositoryModel = teamExplorerContext.ActiveRepository;
+
+            var hostAddress = HostAddress.Create(localRepositoryModel.CloneUrl.Host);
+            var owner = localRepositoryModel.Owner;
+            var name = localRepositoryModel.Name;
+
+            if (query == null)
             {
-                return Observable.Empty<AutoCompleteSuggestion>();
+                query = new Query().Repository(owner: Var(nameof(owner)), name: Var(nameof(name)))
+                .Select(repository =>
+                    repository.MentionableUsers(null, null, null, null)
+                        .AllPages()
+                        .Select(sourceItem => 
+                            new SuggestionItem(sourceItem.Login, 
+                                sourceItem.Name ?? "(unknown)", 
+                                sourceItem.AvatarUrl(null)))
+                        .ToList())
+                .Compile();
             }
 
-            var avatarProviderKey = CurrentRepository.RepositoryHost.Address.WebUri.ToString();
-            var avatarProvider = hostAvatarProvider.Get(avatarProviderKey);
-
-            Func<Uri, IObservable<BitmapSource>> resolveImage = uri =>
-                Observable.Defer(() => ImageCache
-                    .GetImage(uri)
-                    .Catch<BitmapSource, Exception>(_ => Observable.Return(avatarProvider.DefaultUserBitmapImage))
-                    .StartWith(avatarProvider.DefaultUserBitmapImage));
+            var variables = new Dictionary<string, object>
+            {
+                {nameof(owner), owner },
+                {nameof(name), name },
+            };
 
-            return MentionsCache.RetrieveSuggestions(CurrentRepository)
-                .Catch<IReadOnlyList<SuggestionItem>, Exception>(_ => Observable.Empty<IReadOnlyList<SuggestionItem>>())
-                .SelectMany(x => x.ToObservable())
-                .Where(suggestion => !String.IsNullOrEmpty(suggestion.Name)) // Just being extra cautious
-                .Select(suggestion =>
-                    new AutoCompleteSuggestion(suggestion.Name, suggestion.Description, resolveImage(suggestion.IconKey), Prefix));
+            return Observable.FromAsync(async () =>
+            {
+                var connection = await graphqlFactory.CreateConnection(hostAddress);
+                var suggestions = await connection.Run(query, variables);
+                return suggestions.Select(suggestion => new AutoCompleteSuggestion(suggestion.Name,
+                    suggestion.Description,
+                    ResolveImage(suggestion),
+                    Prefix));
+            }).SelectMany(enumerable => enumerable);
         }
 
-        public string Prefix { get { return "@"; } }
-
-        IImageCache ImageCache { get { return imageCache.Value; } }
+        IObservable<BitmapSource> ResolveImage(SuggestionItem uri)
+        {
+            if (uri.ImageUrl != null)
+            {
+                return avatarProvider.GetAvatar(uri.ImageUrl);
+            }
 
-        IMentionsCache MentionsCache { get { return mentionsCache.Value; } }
+            return Observable.Return(AvatarProvider.CreateBitmapImage(DefaultAvatar));
+        }
 
-        RepositoryModel CurrentRepository { get { return currentRepositoryState.Value.SelectedRepository; } }
+        public string Prefix => "@";
     }
 }
diff --git a/src/GitHub.App/ViewModels/CommentViewModel.cs b/src/GitHub.App/ViewModels/CommentViewModel.cs
index b8a640742b..0a750f08a4 100644
--- a/src/GitHub.App/ViewModels/CommentViewModel.cs
+++ b/src/GitHub.App/ViewModels/CommentViewModel.cs
@@ -41,11 +41,14 @@ public class CommentViewModel : ViewModelBase, ICommentViewModel
         /// Initializes a new instance of the <see cref="CommentViewModel"/> class.
         /// </summary>
         /// <param name="commentService">The comment service.</param>
+        /// <param name="autoCompleteAdvisor">The auto complete advisor.</param>
         [ImportingConstructor]
-        public CommentViewModel(ICommentService commentService)
+        public CommentViewModel(ICommentService commentService, IAutoCompleteAdvisor autoCompleteAdvisor)
         {
             Guard.ArgumentNotNull(commentService, nameof(commentService));
+            Guard.ArgumentNotNull(autoCompleteAdvisor, nameof(autoCompleteAdvisor));
 
+            AutoCompleteAdvisor = autoCompleteAdvisor;
             this.commentService = commentService;
 
             var canDeleteObservable = this.WhenAnyValue(
@@ -190,6 +193,9 @@ public ICommentThreadViewModel Thread
         /// <inheritdoc/>
         public ReactiveCommand<Unit, Unit> Delete { get; }
 
+        /// <inheritdoc/>
+        public IAutoCompleteAdvisor AutoCompleteAdvisor { get; }
+
         /// <inheritdoc/>
         public Task InitializeAsync(
             ICommentThreadViewModel thread,
diff --git a/src/GitHub.App/ViewModels/Documents/IssueishCommentViewModel.cs b/src/GitHub.App/ViewModels/Documents/IssueishCommentViewModel.cs
index 184406eb1a..44db887114 100644
--- a/src/GitHub.App/ViewModels/Documents/IssueishCommentViewModel.cs
+++ b/src/GitHub.App/ViewModels/Documents/IssueishCommentViewModel.cs
@@ -23,9 +23,10 @@ public sealed class IssueishCommentViewModel : CommentViewModel, IIssueishCommen
         /// Initializes a new instance of the <see cref="CommentViewModel"/> class.
         /// </summary>
         /// <param name="commentService">The comment service.</param>
+        /// <param name="autoCompleteAdvisor"></param>
         [ImportingConstructor]
-        public IssueishCommentViewModel(ICommentService commentService)
-            : base(commentService)
+        public IssueishCommentViewModel(ICommentService commentService, IAutoCompleteAdvisor autoCompleteAdvisor)
+            : base(commentService, autoCompleteAdvisor)
         {
             CloseOrReopen = ReactiveCommand.CreateFromTask(
                 DoCloseOrReopen,
diff --git a/src/GitHub.App/ViewModels/GitHubPane/PullRequestCreationViewModel.cs b/src/GitHub.App/ViewModels/GitHubPane/PullRequestCreationViewModel.cs
index 89f8e37c50..bd25c85c52 100644
--- a/src/GitHub.App/ViewModels/GitHubPane/PullRequestCreationViewModel.cs
+++ b/src/GitHub.App/ViewModels/GitHubPane/PullRequestCreationViewModel.cs
@@ -18,6 +18,7 @@
 using GitHub.Models.Drafts;
 using GitHub.Primitives;
 using GitHub.Services;
+using GitHub.UI;
 using GitHub.Validation;
 using Octokit;
 using ReactiveUI;
@@ -51,8 +52,9 @@ public PullRequestCreationViewModel(
             IPullRequestService service,
             INotificationService notifications,
             IMessageDraftStore draftStore,
-            IGitService gitService)
-            : this(modelServiceFactory, service, notifications, draftStore, gitService, DefaultScheduler.Instance)
+            IGitService gitService,
+            IAutoCompleteAdvisor autoCompleteAdvisor)
+            : this(modelServiceFactory, service, notifications, draftStore, gitService, autoCompleteAdvisor, DefaultScheduler.Instance)
         {
         }
 
@@ -62,6 +64,7 @@ public PullRequestCreationViewModel(
             INotificationService notifications,
             IMessageDraftStore draftStore,
             IGitService gitService,
+            IAutoCompleteAdvisor autoCompleteAdvisor,
             IScheduler timerScheduler)
         {
             Guard.ArgumentNotNull(modelServiceFactory, nameof(modelServiceFactory));
@@ -69,12 +72,14 @@ public PullRequestCreationViewModel(
             Guard.ArgumentNotNull(notifications, nameof(notifications));
             Guard.ArgumentNotNull(draftStore, nameof(draftStore));
             Guard.ArgumentNotNull(gitService, nameof(gitService));
+            Guard.ArgumentNotNull(autoCompleteAdvisor, nameof(autoCompleteAdvisor));
             Guard.ArgumentNotNull(timerScheduler, nameof(timerScheduler));
 
             this.service = service;
             this.modelServiceFactory = modelServiceFactory;
             this.draftStore = draftStore;
             this.gitService = gitService;
+            this.AutoCompleteAdvisor = autoCompleteAdvisor;
             this.timerScheduler = timerScheduler;
 
             this.WhenAnyValue(x => x.Branches)
@@ -336,6 +341,7 @@ protected string GetDraftKey()
 
         public RemoteRepositoryModel GitHubRepository { get { return githubRepository?.Value; } }
         bool IsExecuting { get { return isExecuting.Value; } }
+        public IAutoCompleteAdvisor AutoCompleteAdvisor { get; }
 
         bool initialized;
         bool Initialized
diff --git a/src/GitHub.App/ViewModels/GitHubPane/PullRequestReviewAuthoringViewModel.cs b/src/GitHub.App/ViewModels/GitHubPane/PullRequestReviewAuthoringViewModel.cs
index c263af4585..82ff54359c 100644
--- a/src/GitHub.App/ViewModels/GitHubPane/PullRequestReviewAuthoringViewModel.cs
+++ b/src/GitHub.App/ViewModels/GitHubPane/PullRequestReviewAuthoringViewModel.cs
@@ -45,8 +45,9 @@ public PullRequestReviewAuthoringViewModel(
             IPullRequestEditorService editorService,
             IPullRequestSessionManager sessionManager,
             IMessageDraftStore draftStore,
-            IPullRequestFilesViewModel files)
-            : this(pullRequestService, editorService, sessionManager,draftStore, files, DefaultScheduler.Instance)
+            IPullRequestFilesViewModel files,
+            IAutoCompleteAdvisor autoCompleteAdvisor)
+            : this(pullRequestService, editorService, sessionManager,draftStore, files, autoCompleteAdvisor, DefaultScheduler.Instance)
         {
         }
 
@@ -56,12 +57,14 @@ public PullRequestReviewAuthoringViewModel(
             IPullRequestSessionManager sessionManager,
             IMessageDraftStore draftStore,
             IPullRequestFilesViewModel files,
+            IAutoCompleteAdvisor autoCompleteAdvisor,
             IScheduler timerScheduler)
         {
             Guard.ArgumentNotNull(editorService, nameof(editorService));
             Guard.ArgumentNotNull(sessionManager, nameof(sessionManager));
             Guard.ArgumentNotNull(draftStore, nameof(draftStore));
             Guard.ArgumentNotNull(files, nameof(files));
+            Guard.ArgumentNotNull(autoCompleteAdvisor, nameof(autoCompleteAdvisor));
             Guard.ArgumentNotNull(timerScheduler, nameof(timerScheduler));
 
             this.pullRequestService = pullRequestService;
@@ -77,6 +80,7 @@ public PullRequestReviewAuthoringViewModel(
                 .ToProperty(this, x => x.CanApproveRequestChanges);
 
             Files = files;
+            AutoCompleteAdvisor = autoCompleteAdvisor;
 
             var hasBodyOrComments = this.WhenAnyValue(
                 x => x.Body,
@@ -118,6 +122,9 @@ public PullRequestDetailModel PullRequestModel
         /// <inheritdoc/>
         public IPullRequestFilesViewModel Files { get; }
 
+        /// <inheritdoc/>
+        public IAutoCompleteAdvisor AutoCompleteAdvisor { get; }
+
         /// <inheritdoc/>
         public string Body
         {
diff --git a/src/GitHub.App/ViewModels/PullRequestReviewCommentViewModel.cs b/src/GitHub.App/ViewModels/PullRequestReviewCommentViewModel.cs
index 1d47330c88..4a2c1a8e97 100644
--- a/src/GitHub.App/ViewModels/PullRequestReviewCommentViewModel.cs
+++ b/src/GitHub.App/ViewModels/PullRequestReviewCommentViewModel.cs
@@ -25,10 +25,12 @@ public class PullRequestReviewCommentViewModel : CommentViewModel, IPullRequestR
         /// <summary>
         /// Initializes a new instance of the <see cref="PullRequestReviewCommentViewModel"/> class.
         /// </summary>
-        /// <param name="commentService">The comment service</param>
+        /// <param name="commentService">The comment service.</param>
+        /// <param name="autoCompleteAdvisor">The auto complete advisor.</param>
         [ImportingConstructor]
-        public PullRequestReviewCommentViewModel(ICommentService commentService)
-            : base(commentService)
+        public PullRequestReviewCommentViewModel(ICommentService commentService,
+            IAutoCompleteAdvisor autoCompleteAdvisor)
+            : base(commentService, autoCompleteAdvisor)
         {
             canStartReview = this.WhenAnyValue(
                 x => x.IsPending,
diff --git a/src/GitHub.Exports.Reactive/ViewModels/GitHubPane/IPullRequestCreationViewModel.cs b/src/GitHub.Exports.Reactive/ViewModels/GitHubPane/IPullRequestCreationViewModel.cs
index a072853cbe..fb201f3ab7 100644
--- a/src/GitHub.Exports.Reactive/ViewModels/GitHubPane/IPullRequestCreationViewModel.cs
+++ b/src/GitHub.Exports.Reactive/ViewModels/GitHubPane/IPullRequestCreationViewModel.cs
@@ -4,6 +4,7 @@
 using ReactiveUI;
 using System.Threading.Tasks;
 using System.Reactive;
+using GitHub.Services;
 
 namespace GitHub.ViewModels.GitHubPane
 {
@@ -16,6 +17,8 @@ public interface IPullRequestCreationViewModel : IPanePageViewModel
         ReactiveCommand<Unit, Unit> Cancel { get; }
         string PRTitle { get; set; }
         ReactivePropertyValidator TitleValidator { get; }
+        IAutoCompleteAdvisor AutoCompleteAdvisor { get; }
+
         Task InitializeAsync(LocalRepositoryModel repository, IConnection connection);
     }
 }
diff --git a/src/GitHub.Exports.Reactive/ViewModels/GitHubPane/IPullRequestReviewAuthoringViewModel.cs b/src/GitHub.Exports.Reactive/ViewModels/GitHubPane/IPullRequestReviewAuthoringViewModel.cs
index e0be2242d9..6d6137050a 100644
--- a/src/GitHub.Exports.Reactive/ViewModels/GitHubPane/IPullRequestReviewAuthoringViewModel.cs
+++ b/src/GitHub.Exports.Reactive/ViewModels/GitHubPane/IPullRequestReviewAuthoringViewModel.cs
@@ -3,6 +3,7 @@
 using System.Reactive;
 using System.Threading.Tasks;
 using GitHub.Models;
+using GitHub.Services;
 using ReactiveUI;
 
 namespace GitHub.ViewModels.GitHubPane
@@ -87,6 +88,11 @@ public interface IPullRequestReviewAuthoringViewModel : IPanePageViewModel, IDis
         /// </summary>
         ReactiveCommand<Unit, Unit> Cancel { get; }
 
+        /// <summary>
+        /// Provides an AutoCompleteAdvisor.
+        /// </summary>
+        IAutoCompleteAdvisor AutoCompleteAdvisor { get; }
+
         /// <summary>
         /// Initializes the view model for creating a new review.
         /// </summary>
diff --git a/src/GitHub.Exports.Reactive/ViewModels/ICommentViewModel.cs b/src/GitHub.Exports.Reactive/ViewModels/ICommentViewModel.cs
index ce35d8a3ff..be6d97e13b 100644
--- a/src/GitHub.Exports.Reactive/ViewModels/ICommentViewModel.cs
+++ b/src/GitHub.Exports.Reactive/ViewModels/ICommentViewModel.cs
@@ -1,5 +1,6 @@
 using System;
 using System.Reactive;
+using GitHub.Services;
 using ReactiveUI;
 
 namespace GitHub.ViewModels
@@ -119,5 +120,10 @@ public interface ICommentViewModel : IViewModel
         /// Deletes a comment.
         /// </summary>
         ReactiveCommand<Unit, Unit> Delete { get; }
+
+        /// <summary>
+        /// Provides an AutoCompleteAdvisor.
+        /// </summary>
+        IAutoCompleteAdvisor AutoCompleteAdvisor { get; }
     }
 }
\ No newline at end of file
diff --git a/src/GitHub.Extensions/ReflectionExtensions.cs b/src/GitHub.Extensions/ReflectionExtensions.cs
index e69c65f1d5..df10dba2f4 100644
--- a/src/GitHub.Extensions/ReflectionExtensions.cs
+++ b/src/GitHub.Extensions/ReflectionExtensions.cs
@@ -4,6 +4,7 @@
 using System.Globalization;
 using System.Linq;
 using System.Reflection;
+using System.Runtime.Serialization;
 
 namespace GitHub.Extensions
 {
@@ -53,5 +54,20 @@ public static string GetCustomAttributeValue<T>(this Assembly assembly, string p
             var value = propertyInfo.GetValue(attribute, null);
             return value.ToString();
         }
+
+        public static T CreateUninitialized<T>()
+        {
+            // WARNING: THIS METHOD IS PURE EVIL!
+            // Only use this in cases where T is sealed and has an internal ctor and 
+            // you're SURE the API you're passing it into won't do anything interesting with it.
+            // Even then, consider refactoring.
+            return (T)FormatterServices.GetUninitializedObject(typeof(T));
+        }
+
+        public static void Invoke(object obj, string methodName, params object[] parameters)
+        {
+            var method = obj.GetType().GetMethod(methodName, BindingFlags.Instance | BindingFlags.NonPublic);
+            method.Invoke(obj, parameters);
+        }
     }
 }
diff --git a/src/GitHub.UI/Assets/Controls/AutoCompleteBox.xaml b/src/GitHub.UI/Assets/Controls/AutoCompleteBox.xaml
index 1a1a950e6b..6d10b00ade 100644
--- a/src/GitHub.UI/Assets/Controls/AutoCompleteBox.xaml
+++ b/src/GitHub.UI/Assets/Controls/AutoCompleteBox.xaml
@@ -9,6 +9,7 @@
     xmlns:sys="clr-namespace:System;assembly=mscorlib"
     xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
     xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
+    xmlns:vs="clr-namespace:Microsoft.VisualStudio.PlatformUI;assembly=Microsoft.VisualStudio.Shell.14.0"
     xmlns:ui="clr-namespace:GitHub.UI">
 
     <!--  CommonValidationToolTipTemplate  -->
@@ -59,62 +60,51 @@
         </Grid>
     </ControlTemplate>
 
-
+    <ControlTemplate x:Key="ListViewItemControlTemplate" TargetType="{x:Type ListBoxItem}">
+        <Border BorderBrush="{TemplateBinding BorderBrush}"
+                BorderThickness="{TemplateBinding BorderThickness}"
+                Background="{TemplateBinding Background}"
+                SnapsToDevicePixels="True"
+                Padding="{TemplateBinding Padding}">
+            <ContentPresenter Content="{TemplateBinding Content}"
+                              ContentTemplate="{TemplateBinding ContentTemplate}"
+                              ContentTemplateSelector="{TemplateBinding ContentTemplateSelector}" />
+        </Border>
+    </ControlTemplate>
+    
     <Style x:Key="AutoCompleteListItemContainerStyle" TargetType="{x:Type ListBoxItem}">
-        <Setter Property="SnapsToDevicePixels" Value="True"/>
-        <Setter Property="Padding" Value="5,0,10,0"/>
-        <Setter Property="HorizontalContentAlignment" Value="{Binding HorizontalContentAlignment, RelativeSource={RelativeSource AncestorType={x:Type ItemsControl}}}"/>
-        <Setter Property="VerticalContentAlignment" Value="{Binding VerticalContentAlignment, RelativeSource={RelativeSource AncestorType={x:Type ItemsControl}}}"/>
-        <Setter Property="Background" Value="{StaticResource GHBoxBackgroundBrush}"/>
-        <Setter Property="Foreground" Value="{StaticResource GHBoxTextBrush}"/>
-        <Setter Property="BorderBrush" Value="Transparent"/>
-        <Setter Property="BorderThickness" Value="0"/>
-        <Setter Property="FocusVisualStyle" Value="{StaticResource NoMarginFocusVisual}"/>
-        <Setter Property="Template">
-            <Setter.Value>
-                <ControlTemplate TargetType="{x:Type ListBoxItem}">
-                    <Border x:Name="Bd" BorderThickness="{TemplateBinding BorderThickness}" Background="{TemplateBinding Background}" Padding="{TemplateBinding Padding}" SnapsToDevicePixels="true">
-                        <ContentPresenter HorizontalAlignment="{TemplateBinding HorizontalContentAlignment}" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" VerticalAlignment="{TemplateBinding VerticalContentAlignment}"/>
-                    </Border>
-                    <ControlTemplate.Triggers>
-                        <MultiTrigger>
-                            <MultiTrigger.Conditions>
-                                <Condition Property="IsMouseOver" Value="True"/>
-                            </MultiTrigger.Conditions>
-                            <Setter Property="BorderBrush" TargetName="Bd" Value="{StaticResource GHBoxHoverBackgroundBrush}"/>
-                        </MultiTrigger>
-                        <MultiTrigger>
-                            <MultiTrigger.Conditions>
-                                <Condition Property="Selector.IsSelectionActive" Value="False"/>
-                                <Condition Property="IsSelected" Value="True"/>
-                            </MultiTrigger.Conditions>
-                            <Setter Property="Background" Value="{StaticResource GHBoxSelectedBackgroundBrush}"/>
-                            <Setter Property="Foreground" Value="{StaticResource GHBoxSelectedTextBrush}"/>
-                        </MultiTrigger>
-                        <MultiTrigger>
-                            <MultiTrigger.Conditions>
-                                <Condition Property="Selector.IsSelectionActive" Value="True"/>
-                                <Condition Property="IsSelected" Value="True"/>
-                            </MultiTrigger.Conditions>
-                            <Setter Property="Background" Value="{StaticResource GHBoxActiveSelectionBackgroundBrush}"/>
-                            <Setter Property="Foreground" Value="{StaticResource GHBoxActiveSelectionTextBrush}"/>
-                        </MultiTrigger>
-                        <Trigger Property="IsEnabled" Value="False">
-                            <Setter Property="Opacity" TargetName="Bd" Value="0.3"/>
-                        </Trigger>
-                    </ControlTemplate.Triggers>
-                </ControlTemplate>
-            </Setter.Value>
-        </Setter>
+        <Setter Property="BorderThickness" Value="0" />
+        <Setter Property="Padding" Value="5,3,3,3" />
+        <Setter Property="Template" Value="{StaticResource ListViewItemControlTemplate}" />
+        <Style.Triggers>
+            <Trigger Property="IsMouseOver" Value="True">
+                <Setter Property="Background" Value="{DynamicResource {x:Static vs:ThemedDialogColors.ListItemMouseOverBrushKey}}" />
+                <Setter Property="Foreground" Value="{DynamicResource {x:Static vs:ThemedDialogColors.ListItemMouseOverTextBrushKey}}" />
+            </Trigger>
+            <Trigger Property="IsSelected" Value="true">
+                <Setter Property="Background" Value="{DynamicResource {x:Static vs:ThemedDialogColors.SelectedItemInactiveBrushKey}}" />
+                <Setter Property="Foreground" Value="{DynamicResource {x:Static vs:ThemedDialogColors.SelectedItemInactiveTextBrushKey}}" />
+            </Trigger>
+            <MultiTrigger>
+                <MultiTrigger.Conditions>
+                    <Condition Property="IsSelected" Value="True" />
+                    <Condition Property="Selector.IsSelectionActive" Value="True" />
+                </MultiTrigger.Conditions>
+                <Setter Property="Background" Value="{DynamicResource {x:Static vs:ThemedDialogColors.SelectedItemActiveBrushKey}}" />
+                <Setter Property="Foreground" Value="{DynamicResource {x:Static vs:ThemedDialogColors.SelectedItemActiveTextBrushKey}}" />
+            </MultiTrigger>
+            <Trigger Property="IsEnabled" Value="False">
+                <Setter Property="Foreground" Value="{DynamicResource {x:Static vs:ThemedDialogColors.ListItemDisabledTextBrushKey}}" />
+            </Trigger>
+        </Style.Triggers>
     </Style>
-
     
     <!--  input:AutoCompleteBox  -->
     <Style TargetType="ui:AutoCompleteBox">
         <Setter Property="IsTabStop" Value="False" />
         <Setter Property="Padding" Value="2" />
-        <Setter Property="Background" Value="{StaticResource DefaultBackgroundBrush}" />
-        <Setter Property="Foreground" Value="{StaticResource GHTextBrush}" />
+        <Setter Property="Background" Value="{DynamicResource {x:Static vs:ThemedDialogColors.WindowPanelBrushKey}}" />
+        <Setter Property="Foreground" Value="{DynamicResource {x:Static vs:ThemedDialogColors.WindowPanelTextBrushKey}}" />
         <Setter Property="MinWidth" Value="45" />
         <Setter Property="ItemContainerStyle" Value="{StaticResource AutoCompleteListItemContainerStyle}" />
 
@@ -125,6 +115,7 @@
                         <ContentPresenter
                             x:Name="Text"
                             Content="{Binding InputElement.Control, RelativeSource={RelativeSource TemplatedParent}}"/>
+                        <!-- TODO: What should we use for validation BorderBrush? -->
                         <Border
                             x:Name="ValidationErrorElement"
                             Visibility="Collapsed"
@@ -174,7 +165,7 @@
                                     x:Name="PopupBorder"
                                     HorizontalAlignment="Stretch"
                                     Opacity="0"
-                                    BorderBrush="#B0B0B0"
+                                    BorderBrush="{DynamicResource {x:Static vs:CommonControlsColors.TextBoxBorderFocusedBrushKey}}"
                                     BorderThickness="1">
                                     <ListBox
                                         x:Name="Selector"
diff --git a/src/GitHub.UI/Controls/AutoCompleteBox/AutoCompleteBox.cs b/src/GitHub.UI/Controls/AutoCompleteBox/AutoCompleteBox.cs
index 7c6075caa0..013c3e40e9 100644
--- a/src/GitHub.UI/Controls/AutoCompleteBox/AutoCompleteBox.cs
+++ b/src/GitHub.UI/Controls/AutoCompleteBox/AutoCompleteBox.cs
@@ -169,11 +169,11 @@ public int MinimumPopulateDelay
 
         /// <summary>
         /// Identifies the
-        /// <see cref="P:GitHub.UI.AutoCompleteBox.MinimumPopulateDelay" />
+        /// <see cref="MinimumPopulateDelay" />
         /// dependency property.
         /// </summary>
         /// <value>The identifier for the
-        /// <see cref="P:GitHub.UI.AutoCompleteBox.MinimumPopulateDelay" />
+        /// <see cref="MinimumPopulateDelay" />
         /// dependency property.</value>
         public static readonly DependencyProperty MinimumPopulateDelayProperty =
             DependencyProperty.Register(
@@ -221,10 +221,10 @@ private static void OnMinimumPopulateDelayPropertyChanged(DependencyObject d, De
         }
 
         /// <summary>
-        /// Gets or sets the <see cref="T:System.Windows.DataTemplate" /> used
+        /// Gets or sets the <see cref="DataTemplate" /> used
         /// to display each item in the drop-down portion of the control.
         /// </summary>
-        /// <value>The <see cref="T:System.Windows.DataTemplate" /> used to
+        /// <value>The <see cref="DataTemplate" /> used to
         /// display each item in the drop-down. The default is null.</value>
         /// <remarks>
         /// You use the ItemTemplate property to specify the visualization 
@@ -242,11 +242,11 @@ public DataTemplate ItemTemplate
 
         /// <summary>
         /// Identifies the
-        /// <see cref="P:GitHub.UI.AutoCompleteBox.ItemTemplate" />
+        /// <see cref="AutoCompleteBox.ItemTemplate" />
         /// dependency property.
         /// </summary>
         /// <value>The identifier for the
-        /// <see cref="P:GitHub.UI.AutoCompleteBox.ItemTemplate" />
+        /// <see cref="AutoCompleteBox.ItemTemplate" />
         /// dependency property.</value>
         public static readonly DependencyProperty ItemTemplateProperty =
             DependencyProperty.Register(
@@ -277,11 +277,11 @@ public Style ItemContainerStyle
 
         /// <summary>
         /// Identifies the
-        /// <see cref="P:GitHub.UI.AutoCompleteBox.ItemContainerStyle" />
+        /// <see cref="AutoCompleteBox.ItemContainerStyle" />
         /// dependency property.
         /// </summary>
         /// <value>The identifier for the
-        /// <see cref="P:GitHub.UI.AutoCompleteBox.ItemContainerStyle" />
+        /// <see cref="AutoCompleteBox.ItemContainerStyle" />
         /// dependency property.</value>
         public static readonly DependencyProperty ItemContainerStyleProperty =
             DependencyProperty.Register(
@@ -307,11 +307,11 @@ public Style TextBoxStyle
 
         /// <summary>
         /// Identifies the
-        /// <see cref="P:GitHub.UI.AutoCompleteBox.TextBoxStyle" />
+        /// <see cref="AutoCompleteBox.TextBoxStyle" />
         /// dependency property.
         /// </summary>
         /// <value>The identifier for the
-        /// <see cref="P:GitHub.UI.AutoCompleteBox.TextBoxStyle" />
+        /// <see cref="AutoCompleteBox.TextBoxStyle" />
         /// dependency property.</value>
         public static readonly DependencyProperty TextBoxStyleProperty =
             DependencyProperty.Register(
@@ -336,11 +336,11 @@ public double MaxDropDownHeight
 
         /// <summary>
         /// Identifies the
-        /// <see cref="P:GitHub.UI.AutoCompleteBox.MaxDropDownHeight" />
+        /// <see cref="AutoCompleteBox.MaxDropDownHeight" />
         /// dependency property.
         /// </summary>
         /// <value>The identifier for the
-        /// <see cref="P:GitHub.UI.AutoCompleteBox.MaxDropDownHeight" />
+        /// <see cref="AutoCompleteBox.MaxDropDownHeight" />
         /// dependency property.</value>
         public static readonly DependencyProperty MaxDropDownHeightProperty =
             DependencyProperty.Register(
@@ -415,11 +415,11 @@ void HandleShortcutSupport(bool value)
 
         /// <summary>
         /// Identifies the
-        /// <see cref="P:GitHub.UI.AutoCompleteBox.IsDropDownOpen" />
+        /// <see cref="AutoCompleteBox.IsDropDownOpen" />
         /// dependency property.
         /// </summary>
         /// <value>The identifier for the
-        /// <see cref="P:GitHub.UI.AutoCompleteBox.IsDropDownOpen" />
+        /// <see cref="AutoCompleteBox.IsDropDownOpen" />
         /// dependency property.</value>
         public static readonly DependencyProperty IsDropDownOpenProperty =
             DependencyProperty.Register(
@@ -473,11 +473,11 @@ public IEnumerable ItemsSource
 
         /// <summary>
         /// Identifies the
-        /// <see cref="P:GitHub.UI.AutoCompleteBox.ItemsSource" />
+        /// <see cref="AutoCompleteBox.ItemsSource" />
         /// dependency property.
         /// </summary>
         /// <value>The identifier for the
-        /// <see cref="P:GitHub.UI.AutoCompleteBox.ItemsSource" />
+        /// <see cref="AutoCompleteBox.ItemsSource" />
         /// dependency property.</value>
         public static readonly DependencyProperty ItemsSourceProperty =
             DependencyProperty.Register(
@@ -516,11 +516,11 @@ public object SelectedItem
 
         /// <summary>
         /// Identifies the
-        /// <see cref="P:GitHub.UI.AutoCompleteBox.SelectedItem" />
+        /// <see cref="AutoCompleteBox.SelectedItem" />
         /// dependency property.
         /// </summary>
         /// <value>The identifier the
-        /// <see cref="P:GitHub.UI.AutoCompleteBox.SelectedItem" />
+        /// <see cref="AutoCompleteBox.SelectedItem" />
         /// dependency property.</value>
         public static readonly DependencyProperty SelectedItemProperty =
             DependencyProperty.Register(
@@ -575,11 +575,11 @@ public string Text
 
         /// <summary>
         /// Identifies the
-        /// <see cref="P:GitHub.UI.AutoCompleteBox.Text" />
+        /// <see cref="AutoCompleteBox.Text" />
         /// dependency property.
         /// </summary>
         /// <value>The identifier for the
-        /// <see cref="P:GitHub.UI.AutoCompleteBox.Text" />
+        /// <see cref="AutoCompleteBox.Text" />
         /// dependency property.</value>
         public static readonly DependencyProperty TextProperty =
             DependencyProperty.Register(
@@ -620,7 +620,7 @@ private static void OnTextPropertyChanged(DependencyObject d, DependencyProperty
         /// Gets or sets the Text template part.
         /// </summary>
         [SuppressMessage("Microsoft.Design", "CA1062:Validate arguments of public methods", MessageId = "0")]
-        protected internal IAutoCompleteTextInput TextBox
+        public IAutoCompleteTextInput TextBox
         {
             get { return textInput; }
             set { UpdateTextBox(value); }
@@ -646,8 +646,8 @@ void UpdateTextBox(IAutoCompleteTextInput value)
                     supportsShortcutOriginalValue = shortcutContainer.SupportsKeyboardShortcuts;
                 }
 
-                SubscribeToEvent("OnTextBoxTextChanged", ObserveTextBoxChanges()
-                    .Subscribe(shouldPopulate =>
+                SubscribeToEvent("OnTextBoxTextChanged", 
+                    ObserveTextBoxChanges().Subscribe(shouldPopulate =>
                     {
                         if (shouldPopulate)
                         {
@@ -701,12 +701,12 @@ IObservable<bool> ObserveTextBoxChanges()
         /// <value>The selection adapter used to populate the drop-down with a
         /// list of selectable items.</value>
         /// <remarks>
-        /// You can use this property when you create an automation peer to 
+        /// You can use this property when you create an automation peer to sw
         /// use with AutoCompleteBox or deriving from AutoCompleteBox to 
         /// create a custom control.
         /// </remarks>
         [SuppressMessage("Microsoft.Design", "CA1062:Validate arguments of public methods", MessageId = "0")]
-        protected internal ISelectionAdapter SelectionAdapter
+        public ISelectionAdapter SelectionAdapter
         {
             get { return adapter; }
             set
@@ -740,6 +740,34 @@ public IAutoCompleteAdvisor Advisor
             set;
         }
 
+        /// <summary>
+        /// Identifies the
+        /// <see cref="IAutoCompleteAdvisor" />
+        /// dependency property.
+        /// </summary>
+        /// <value>The identifier for the
+        /// <see cref="IAutoCompleteAdvisor" />
+        /// dependency property.</value>
+        public static readonly DependencyProperty AdvisorProperty =
+            DependencyProperty.Register(
+                "Advisor",
+                typeof(IAutoCompleteAdvisor),
+                typeof(AutoCompleteBox),
+                new PropertyMetadata(null, OnAdvisorPropertyChanged));
+
+        /// <summary>
+        /// AdvisorProperty property changed handler.
+        /// </summary>
+        /// <param name="d">AutoCompleteBox that changed its Advisor.</param>
+        /// <param name="e">Event arguments.</param>
+        private static void OnAdvisorPropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
+        {
+            var source = d as AutoCompleteBox;
+            if (source == null) return;
+
+            source.Advisor = (IAutoCompleteAdvisor)e.NewValue;
+        }
+
         /// <summary>
         /// Builds the visual tree for the
         /// <see cref="GitHub.UI.AutoCompleteBox" /> control
@@ -871,9 +899,9 @@ private void RaiseExpandCollapseAutomationEvent(bool oldValue, bool newValue)
         /// Handles the PreviewKeyDown event on the TextBox for WPF.
         /// </summary>
         /// <param name="e">The event data.</param>
-        private void OnTextBoxPreviewKeyDown(KeyEventArgs e)
+        private void OnTextBoxPreviewKeyDown(EventPattern<KeyEventArgs> e)
         {
-            OnKeyDown(e);
+            OnKeyDown(e.EventArgs);
         }
 
         /// <summary>
@@ -1051,10 +1079,10 @@ void DismissDropDown()
 
         /// <summary>
         /// Converts the specified object to a string by using the
-        /// <see cref="P:System.Windows.Data.Binding.Converter" /> and
-        /// <see cref="P:System.Windows.Data.Binding.ConverterCulture" /> values
+        /// <see cref="System.Windows.Data.Binding.Converter" /> and
+        /// <see cref="System.Windows.Data.Binding.ConverterCulture" /> values
         /// of the binding object specified by the
-        /// <see cref="P:GitHub.UI.AutoCompleteBox.ValueMemberBinding" />
+        /// <see cref="AutoCompleteBox.ValueMemberBinding" />
         /// property.
         /// </summary>
         /// <param name="value">The object to format as a string.</param>
@@ -1121,7 +1149,7 @@ private void OnTextPropertyChanged(string newText)
         /// <summary>
         /// Notifies the
         /// <see cref="GitHub.UI.AutoCompleteBox" /> that the
-        /// <see cref="P:GitHub.UI.AutoCompleteBox.ItemsSource" />
+        /// <see cref="AutoCompleteBox.ItemsSource" />
         /// property has been set and the data can be filtered to provide
         /// possible matches in the drop-down.
         /// </summary>
@@ -1493,10 +1521,10 @@ protected override void OnKeyDown(KeyEventArgs e)
             // Standard drop down navigation
             switch (e.Key)
             {
-                case Key.F4:
-                    IsDropDownOpen = !IsDropDownOpen;
-                    e.Handled = true;
-                    break;
+//                case Key.F4:
+//                    IsDropDownOpen = !IsDropDownOpen;
+//                    e.Handled = true;
+//                    break;
 
                 case Key.Enter:
                     if (IsDropDownOpen && SelectedItem != null)
@@ -1573,11 +1601,11 @@ public IAutoCompleteTextInput InputElement
 
         /// <summary>
         /// Identifies the
-        /// <see cref="P:GitHub.UI.AutoCompleteBox.MinimumPopulateDelay" />
+        /// <see cref="MinimumPopulateDelay" />
         /// dependency property.
         /// </summary>
         /// <value>The identifier for the
-        /// <see cref="P:GitHub.UI.AutoCompleteBox.MinimumPopulateDelay" />
+        /// <see cref="MinimumPopulateDelay" />
         /// dependency property.</value>
         public static readonly DependencyProperty InputElementProperty =
             DependencyProperty.Register(
diff --git a/src/GitHub.UI/Controls/AutoCompleteBox/AutoCompleteTextInputExtensions.cs b/src/GitHub.UI/Controls/AutoCompleteBox/AutoCompleteTextInputExtensions.cs
index 4815b5d045..abad932547 100644
--- a/src/GitHub.UI/Controls/AutoCompleteBox/AutoCompleteTextInputExtensions.cs
+++ b/src/GitHub.UI/Controls/AutoCompleteBox/AutoCompleteTextInputExtensions.cs
@@ -24,8 +24,10 @@ public static string GetExpandedText(this IAutoCompleteTextInput textInput, stri
             int offset = completionOffset;
 
             var currentText = textInput.Text ?? ""; // Playing it safe
-            Debug.Assert(offset <= currentText.Length, "The offset can't be larger than the current text length");
-            Debug.Assert(afterIndex <= currentText.Length, "The afterIndex can't be larger than the current text length");
+
+            if (offset > currentText.Length) throw new InvalidOperationException("The offset can't be larger than the current text length");
+            if (afterIndex > currentText.Length) throw new InvalidOperationException("The afterIndex can't be larger than the current text length");
+
             var before = currentText.Substring(0, offset);
             var after = currentText.Substring(afterIndex);
             string prefix = before + value + " ";
diff --git a/src/GitHub.UI/Controls/AutoCompleteBox/IAutoCompleteTextInput.cs b/src/GitHub.UI/Controls/AutoCompleteBox/IAutoCompleteTextInput.cs
index 1128c232ff..95446edf45 100644
--- a/src/GitHub.UI/Controls/AutoCompleteBox/IAutoCompleteTextInput.cs
+++ b/src/GitHub.UI/Controls/AutoCompleteBox/IAutoCompleteTextInput.cs
@@ -1,6 +1,7 @@
 using System;
 using System.ComponentModel;
 using System.Diagnostics.CodeAnalysis;
+using System.Reactive;
 using System.Windows;
 using System.Windows.Controls;
 using System.Windows.Input;
@@ -18,9 +19,9 @@ public interface IAutoCompleteTextInput : INotifyPropertyChanged
         int SelectionStart { get; }
         int SelectionLength { get; }
         string Text { get; set; }
-        IObservable<KeyEventArgs> PreviewKeyDown { get; }
-        IObservable<RoutedEventArgs> SelectionChanged { get; }
-        IObservable<TextChangedEventArgs> TextChanged { get; }
+        IObservable<EventPattern<KeyEventArgs>> PreviewKeyDown { get; }
+        IObservable<EventPattern<RoutedEventArgs>> SelectionChanged { get; }
+        IObservable<EventPattern<TextChangedEventArgs>> TextChanged { get; }
         UIElement Control { get; }
         Point GetPositionFromCharIndex(int charIndex);
         Thickness Margin { get; set; }
diff --git a/src/GitHub.UI/Controls/AutoCompleteBox/ISelectionAdapter.cs b/src/GitHub.UI/Controls/AutoCompleteBox/ISelectionAdapter.cs
index 088514c69a..191d09675d 100644
--- a/src/GitHub.UI/Controls/AutoCompleteBox/ISelectionAdapter.cs
+++ b/src/GitHub.UI/Controls/AutoCompleteBox/ISelectionAdapter.cs
@@ -27,7 +27,7 @@ public interface ISelectionAdapter
 
         /// <summary>
         /// Occurs when the
-        /// <see cref="P:Chat.ISelectionAdapter.SelectedItem" />
+        /// <see cref="ISelectionAdapter.SelectedItem" />
         /// property value changes.
         /// </summary>
         event SelectionChangedEventHandler SelectionChanged;
diff --git a/src/GitHub.UI/Controls/AutoCompleteBox/RichTextBoxAutoCompleteTextInput.cs b/src/GitHub.UI/Controls/AutoCompleteBox/RichTextBoxAutoCompleteTextInput.cs
index c4ac5ce1be..67def11de8 100644
--- a/src/GitHub.UI/Controls/AutoCompleteBox/RichTextBoxAutoCompleteTextInput.cs
+++ b/src/GitHub.UI/Controls/AutoCompleteBox/RichTextBoxAutoCompleteTextInput.cs
@@ -4,6 +4,7 @@
 using System.Diagnostics.CodeAnalysis;
 using System.Globalization;
 using System.IO;
+using System.Reactive;
 using System.Reactive.Linq;
 using System.Text;
 using System.Windows;
@@ -112,15 +113,15 @@ public string Text
             }
         }
 
-        public IObservable<KeyEventArgs> PreviewKeyDown
+        public IObservable<EventPattern<KeyEventArgs>> PreviewKeyDown
         {
             get;
             private set;
         }
 
-        public IObservable<RoutedEventArgs> SelectionChanged { get; private set; }
+        public IObservable<EventPattern<RoutedEventArgs>> SelectionChanged { get; private set; }
 
-        public IObservable<TextChangedEventArgs> TextChanged { get; private set; }
+        public IObservable<EventPattern<TextChangedEventArgs>> TextChanged { get; private set; }
 
         public UIElement Control { get { return textBox; } }
 
@@ -158,15 +159,15 @@ public RichTextBox TextBox
                 {
                     textBox = value;
 
-                    PreviewKeyDown = Observable.FromEvent<KeyEventHandler, KeyEventArgs>(
+                    PreviewKeyDown = Observable.FromEventPattern<KeyEventHandler, KeyEventArgs>(
                         h => textBox.PreviewKeyDown += h,
                         h => textBox.PreviewKeyDown -= h);
 
-                    SelectionChanged = Observable.FromEvent<RoutedEventHandler, RoutedEventArgs>(
+                    SelectionChanged = Observable.FromEventPattern<RoutedEventHandler, RoutedEventArgs>(
                         h => textBox.SelectionChanged += h,
                         h => textBox.SelectionChanged -= h);
 
-                    TextChanged = Observable.FromEvent<TextChangedEventHandler, TextChangedEventArgs>(
+                    TextChanged = Observable.FromEventPattern<TextChangedEventHandler, TextChangedEventArgs>(
                         h => textBox.TextChanged += h,
                         h => textBox.TextChanged -= h);
 
diff --git a/src/GitHub.UI/Controls/AutoCompleteBox/SelectorSelectionAdapter.cs b/src/GitHub.UI/Controls/AutoCompleteBox/SelectorSelectionAdapter.cs
index 1d88f446f5..e3d2aab6b0 100644
--- a/src/GitHub.UI/Controls/AutoCompleteBox/SelectorSelectionAdapter.cs
+++ b/src/GitHub.UI/Controls/AutoCompleteBox/SelectorSelectionAdapter.cs
@@ -61,13 +61,13 @@ public Selector SelectorControl
         }
 
         /// <summary>
-        /// Occurs when the <see cref="P:Chat.SelectorSelectionAdapter.SelectedItem" /> property value changes.
+        /// Occurs when the <see cref="SelectorSelectionAdapter.SelectedItem" /> property value changes.
         /// </summary>
         public event SelectionChangedEventHandler SelectionChanged;
 
         /// <summary>
         /// Occurs when an item is selected and is committed to the underlying
-        /// <see cref="T:System.Windows.Controls.Primitives.Selector" /> control.
+        /// <see cref="System.Windows.Controls.Primitives.Selector" /> control.
         /// </summary>
         public event RoutedEventHandler Commit;
 
@@ -194,9 +194,9 @@ private void OnSelectionChanged(object sender, SelectionChangedEventArgs e)
 
         /// <summary>
         /// Increments the
-        /// <see cref="P:System.Windows.Controls.Primitives.Selector.SelectedIndex" />
+        /// <see cref="Selector.SelectedIndex" />
         /// property of the underlying
-        /// <see cref="T:System.Windows.Controls.Primitives.Selector" />
+        /// <see cref="Selector" />
         /// control.
         /// </summary>
         protected void SelectedIndexIncrement()
@@ -212,9 +212,9 @@ protected void SelectedIndexIncrement()
 
         /// <summary>
         /// Decrements the
-        /// <see cref="P:System.Windows.Controls.Primitives.Selector.SelectedIndex" />
+        /// <see cref="Selector.SelectedIndex" />
         /// property of the underlying
-        /// <see cref="T:System.Windows.Controls.Primitives.Selector" />
+        /// <see cref="Selector" />
         /// control.
         /// </summary>
         protected void SelectedIndexDecrement()
diff --git a/src/GitHub.UI/Controls/AutoCompleteBox/TextBoxAutoCompleteTextInput.cs b/src/GitHub.UI/Controls/AutoCompleteBox/TextBoxAutoCompleteTextInput.cs
index e6cff0d94e..3b46c0a877 100644
--- a/src/GitHub.UI/Controls/AutoCompleteBox/TextBoxAutoCompleteTextInput.cs
+++ b/src/GitHub.UI/Controls/AutoCompleteBox/TextBoxAutoCompleteTextInput.cs
@@ -1,5 +1,6 @@
 using System;
 using System.ComponentModel;
+using System.Reactive;
 using System.Reactive.Linq;
 using System.Windows;
 using System.Windows.Controls;
@@ -51,14 +52,14 @@ public string Text
             set { textBox.Text = value; }
         }
 
-        public IObservable<KeyEventArgs> PreviewKeyDown
+        public IObservable<EventPattern<KeyEventArgs>> PreviewKeyDown
         {
             get;
             private set;
         }
 
-        public IObservable<RoutedEventArgs> SelectionChanged { get; private set; }
-        public IObservable<TextChangedEventArgs> TextChanged { get; private set; }
+        public IObservable<EventPattern<RoutedEventArgs>> SelectionChanged { get; private set; }
+        public IObservable<EventPattern<TextChangedEventArgs>> TextChanged { get; private set; }
         public UIElement Control { get { return textBox; } }
         
         public Point GetPositionFromCharIndex(int charIndex)
@@ -85,15 +86,15 @@ public TextBox TextBox
                 {
                     textBox = value;
 
-                    PreviewKeyDown = Observable.FromEvent<KeyEventHandler, KeyEventArgs>(
+                    PreviewKeyDown = Observable.FromEventPattern<KeyEventHandler, KeyEventArgs>(
                         h => textBox.PreviewKeyDown += h, 
                         h => textBox.PreviewKeyDown -= h);
 
-                    SelectionChanged = Observable.FromEvent<RoutedEventHandler, RoutedEventArgs>(
+                    SelectionChanged = Observable.FromEventPattern<RoutedEventHandler, RoutedEventArgs>(
                         h => textBox.SelectionChanged += h,
                         h => textBox.SelectionChanged -= h);
 
-                    TextChanged = Observable.FromEvent<TextChangedEventHandler, TextChangedEventArgs>(
+                    TextChanged = Observable.FromEventPattern<TextChangedEventHandler, TextChangedEventArgs>(
                         h => textBox.TextChanged += h,
                         h => textBox.TextChanged -= h);
 
diff --git a/src/GitHub.UI/Views/AutoCompleteSuggestionView.xaml b/src/GitHub.UI/Views/AutoCompleteSuggestionView.xaml
index c7869572e6..d0f48cfe2d 100644
--- a/src/GitHub.UI/Views/AutoCompleteSuggestionView.xaml
+++ b/src/GitHub.UI/Views/AutoCompleteSuggestionView.xaml
@@ -20,8 +20,8 @@
                 <RectangleGeometry Rect="0,0,24,24" RadiusX="2" RadiusY="2" />
             </Image.Clip>
         </Image>
-        <TextBlock x:Name="suggestionText" Style="{StaticResource GitHubTextBlock}" VerticalAlignment="Center">
-            <Run x:Name="name" Foreground="{StaticResource GHTextBrush}" Text="Name" /> <Run x:Name="description" Foreground="{StaticResource GHTextSecondaryBrush}" Text="Description" />
+        <TextBlock x:Name="suggestionText" VerticalAlignment="Center">
+            <Run x:Name="name" Text="Name" /> <Run x:Name="description" Text="Description" />
         </TextBlock>
     </StackPanel>
 </UserControl>
diff --git a/src/GitHub.UI/Views/AutoCompleteSuggestionView.xaml.cs b/src/GitHub.UI/Views/AutoCompleteSuggestionView.xaml.cs
index d0c52b33f7..d76f4fb316 100644
--- a/src/GitHub.UI/Views/AutoCompleteSuggestionView.xaml.cs
+++ b/src/GitHub.UI/Views/AutoCompleteSuggestionView.xaml.cs
@@ -2,6 +2,7 @@
 using System.Windows;
 using GitHub.Extensions;
 using GitHub.Extensions.Reactive;
+using GitHub.Models;
 using GitHub.UI;
 using ReactiveUI;
 
diff --git a/src/GitHub.VisualStudio.UI/Styles/ThemeBlue.xaml b/src/GitHub.VisualStudio.UI/Styles/ThemeBlue.xaml
index 8863e8ffb2..02ab52e767 100644
--- a/src/GitHub.VisualStudio.UI/Styles/ThemeBlue.xaml
+++ b/src/GitHub.VisualStudio.UI/Styles/ThemeBlue.xaml
@@ -67,5 +67,57 @@
   <SolidColorBrush x:Key="GitHubMultilineListItemActiveBrush" Color="#FFCCCEDB" />
   <SolidColorBrush x:Key="GitHubFileExpanderHeaderBackgroundBrush" Color="#FFD6DBE9" />
 
-    <SolidColorBrush x:Key="GitHubTimelineEventBackgroundBrush" Color="#FFe1e4e8" />
+  <SolidColorBrush x:Key="GitHubTimelineEventBackgroundBrush" Color="#FFe1e4e8" />
+
+    <!-- Not selected, nor focused -->
+    <Color x:Key="GHBoxTextColor">#333333</Color>
+    <SolidColorBrush x:Key="GHBoxTextBrush" Color="{StaticResource GHBoxTextColor}"
+                     PresentationOptions:Freeze="true" />
+
+    <Color x:Key="GHBoxIconColor">#b7b7b7</Color>
+    <SolidColorBrush x:Key="GHBoxIconBrush" Color="{StaticResource GHBoxIconColor}"
+                     PresentationOptions:Freeze="true" />
+
+    <Color x:Key="GHBoxBackgroundColor">Transparent</Color>
+    <SolidColorBrush x:Key="GHBoxBackgroundBrush" Color="{StaticResource GHBoxBackgroundColor}"
+                     PresentationOptions:Freeze="true" />
+
+    <!-- Selected, not active (focused) -->
+    <Color x:Key="GHBoxSelectedTextColor">#333333</Color>
+    <SolidColorBrush x:Key="GHBoxSelectedTextBrush" Color="{StaticResource GHBoxSelectedTextColor}"
+                     PresentationOptions:Freeze="true" />
+
+    <Color x:Key="GHBoxSelectedIconColor">#b7b7b7</Color>
+    <SolidColorBrush x:Key="GHBoxSelectedIconBrush" Color="{StaticResource GHBoxSelectedIconColor}"
+                     PresentationOptions:Freeze="true" />
+
+    <Color x:Key="GHBoxSelectedBackgroundColor">#e7e7e7</Color>
+    <SolidColorBrush x:Key="GHBoxSelectedBackgroundBrush" Color="{StaticResource GHBoxSelectedBackgroundColor}"
+                     PresentationOptions:Freeze="true" />
+
+    <!-- Selected and active (focused) -->
+    <Color x:Key="GHBoxActiveSelectionTextColor">#ffffff</Color>
+    <SolidColorBrush x:Key="GHBoxActiveSelectionTextBrush" Color="{StaticResource GHBoxActiveSelectionTextColor}"
+                     PresentationOptions:Freeze="true" />
+
+    <Color x:Key="GHBoxActiveSelectionIconColor">#ffffff</Color>
+    <SolidColorBrush x:Key="GHBoxActiveSelectionIconBrush" Color="{StaticResource GHBoxActiveSelectionIconColor}"
+                     PresentationOptions:Freeze="true" />
+
+    <Color x:Key="GHBoxActiveSelectionBackgroundColor">#3998d6</Color>
+    <SolidColorBrush x:Key="GHBoxActiveSelectionBackgroundBrush" Color="{StaticResource GHBoxActiveSelectionBackgroundColor}"
+                     PresentationOptions:Freeze="true" />
+
+    <!-- Hovered (should never be used for selected or active items) -->
+    <Color x:Key="GHBoxHoverTextColor">#0a0a0a</Color>
+    <SolidColorBrush x:Key="GHBoxHoverTextBrush" Color="{StaticResource GHBoxHoverTextColor}"
+                     PresentationOptions:Freeze="true" />
+
+    <Color x:Key="GHBoxHoverIconColor">#909090</Color>
+    <SolidColorBrush x:Key="GHBoxHoverIconBrush" Color="{StaticResource GHBoxHoverIconColor}"
+                     PresentationOptions:Freeze="true" />
+
+    <Color x:Key="GHBoxHoverBackgroundColor">Transparent</Color>
+    <SolidColorBrush x:Key="GHBoxHoverBackgroundBrush" Color="{StaticResource GHBoxHoverBackgroundColor}"
+                     PresentationOptions:Freeze="true" />
 </ResourceDictionary>
\ No newline at end of file
diff --git a/src/GitHub.VisualStudio.UI/Styles/ThemeDark.xaml b/src/GitHub.VisualStudio.UI/Styles/ThemeDark.xaml
index d47c6cbadc..f3ab5a0166 100644
--- a/src/GitHub.VisualStudio.UI/Styles/ThemeDark.xaml
+++ b/src/GitHub.VisualStudio.UI/Styles/ThemeDark.xaml
@@ -67,5 +67,57 @@
   <SolidColorBrush x:Key="GitHubMultilineListItemActiveBrush" Color="#FF3F3F46"/>
   <SolidColorBrush x:Key="GitHubFileExpanderHeaderBackgroundBrush" Color="#FF2D2D30" />
 
-    <SolidColorBrush x:Key="GitHubTimelineEventBackgroundBrush" Color="#FF4b4d50" />
+  <SolidColorBrush x:Key="GitHubTimelineEventBackgroundBrush" Color="#FF4b4d50" />
+
+    <!-- Not selected, nor focused -->
+    <Color x:Key="GHBoxTextColor">#cccccc</Color>
+    <SolidColorBrush x:Key="GHBoxTextBrush" Color="{StaticResource GHBoxTextColor}"
+                     PresentationOptions:Freeze="true" />
+
+    <Color x:Key="GHBoxIconColor">#b7b7b7</Color>
+    <SolidColorBrush x:Key="GHBoxIconBrush" Color="{StaticResource GHBoxIconColor}"
+                     PresentationOptions:Freeze="true" />
+
+    <Color x:Key="GHBoxBackgroundColor">Transparent</Color>
+    <SolidColorBrush x:Key="GHBoxBackgroundBrush" Color="{StaticResource GHBoxBackgroundColor}"
+                     PresentationOptions:Freeze="true" />
+
+    <!-- Selected, not active (focused) -->
+    <Color x:Key="GHBoxSelectedTextColor">#cccccc</Color>
+    <SolidColorBrush x:Key="GHBoxSelectedTextBrush" Color="{StaticResource GHBoxSelectedTextColor}"
+                     PresentationOptions:Freeze="true" />
+
+    <Color x:Key="GHBoxSelectedIconColor">#b7b7b7</Color>
+    <SolidColorBrush x:Key="GHBoxSelectedIconBrush" Color="{StaticResource GHBoxSelectedIconColor}"
+                     PresentationOptions:Freeze="true" />
+
+    <Color x:Key="GHBoxSelectedBackgroundColor">#3e3e3e</Color>
+    <SolidColorBrush x:Key="GHBoxSelectedBackgroundBrush" Color="{StaticResource GHBoxSelectedBackgroundColor}"
+                     PresentationOptions:Freeze="true" />
+
+    <!-- Selected and active (focused) -->
+    <Color x:Key="GHBoxActiveSelectionTextColor">#ffffff</Color>
+    <SolidColorBrush x:Key="GHBoxActiveSelectionTextBrush" Color="{StaticResource GHBoxActiveSelectionTextColor}"
+                     PresentationOptions:Freeze="true" />
+
+    <Color x:Key="GHBoxActiveSelectionIconColor">#ffffff</Color>
+    <SolidColorBrush x:Key="GHBoxActiveSelectionIconBrush" Color="{StaticResource GHBoxActiveSelectionIconColor}"
+                     PresentationOptions:Freeze="true" />
+
+    <Color x:Key="GHBoxActiveSelectionBackgroundColor">#3998d6</Color>
+    <SolidColorBrush x:Key="GHBoxActiveSelectionBackgroundBrush" Color="{StaticResource GHBoxActiveSelectionBackgroundColor}"
+                     PresentationOptions:Freeze="true" />
+
+    <!-- Hovered (should never be used for selected or active items) -->
+    <Color x:Key="GHBoxHoverTextColor">#ffffff</Color>
+    <SolidColorBrush x:Key="GHBoxHoverTextBrush" Color="{StaticResource GHBoxHoverTextColor}"
+                     PresentationOptions:Freeze="true" />
+
+    <Color x:Key="GHBoxHoverIconColor">#ffffff</Color>
+    <SolidColorBrush x:Key="GHBoxHoverIconBrush" Color="{StaticResource GHBoxHoverIconColor}"
+                     PresentationOptions:Freeze="true" />
+
+    <Color x:Key="GHBoxHoverBackgroundColor">Transparent</Color>
+    <SolidColorBrush x:Key="GHBoxHoverBackgroundBrush" Color="{StaticResource GHBoxHoverBackgroundColor}"
+                     PresentationOptions:Freeze="true" />
 </ResourceDictionary>
\ No newline at end of file
diff --git a/src/GitHub.VisualStudio.UI/Styles/ThemeLight.xaml b/src/GitHub.VisualStudio.UI/Styles/ThemeLight.xaml
index 5ccf074b68..1944cfd418 100644
--- a/src/GitHub.VisualStudio.UI/Styles/ThemeLight.xaml
+++ b/src/GitHub.VisualStudio.UI/Styles/ThemeLight.xaml
@@ -67,5 +67,57 @@
   <SolidColorBrush x:Key="GitHubMultilineListItemActiveBrush" Color="#FFCCCEDB"/>
   <SolidColorBrush x:Key="GitHubFileExpanderHeaderBackgroundBrush" Color="#FFEEEEF2" />
 
-    <SolidColorBrush x:Key="GitHubTimelineEventBackgroundBrush" Color="#FFe1e4e8" />
+  <SolidColorBrush x:Key="GitHubTimelineEventBackgroundBrush" Color="#FFe1e4e8" />
+
+    <!-- Not selected, nor focused -->
+    <Color x:Key="GHBoxTextColor">#333333</Color>
+    <SolidColorBrush x:Key="GHBoxTextBrush" Color="{StaticResource GHBoxTextColor}"
+                     PresentationOptions:Freeze="true" />
+
+    <Color x:Key="GHBoxIconColor">#b7b7b7</Color>
+    <SolidColorBrush x:Key="GHBoxIconBrush" Color="{StaticResource GHBoxIconColor}"
+                     PresentationOptions:Freeze="true" />
+
+    <Color x:Key="GHBoxBackgroundColor">Transparent</Color>
+    <SolidColorBrush x:Key="GHBoxBackgroundBrush" Color="{StaticResource GHBoxBackgroundColor}"
+                     PresentationOptions:Freeze="true" />
+
+    <!-- Selected, not active (focused) -->
+    <Color x:Key="GHBoxSelectedTextColor">#333333</Color>
+    <SolidColorBrush x:Key="GHBoxSelectedTextBrush" Color="{StaticResource GHBoxSelectedTextColor}"
+                     PresentationOptions:Freeze="true" />
+
+    <Color x:Key="GHBoxSelectedIconColor">#b7b7b7</Color>
+    <SolidColorBrush x:Key="GHBoxSelectedIconBrush" Color="{StaticResource GHBoxSelectedIconColor}"
+                     PresentationOptions:Freeze="true" />
+
+    <Color x:Key="GHBoxSelectedBackgroundColor">#e7e7e7</Color>
+    <SolidColorBrush x:Key="GHBoxSelectedBackgroundBrush" Color="{StaticResource GHBoxSelectedBackgroundColor}"
+                     PresentationOptions:Freeze="true" />
+
+    <!-- Selected and active (focused) -->
+    <Color x:Key="GHBoxActiveSelectionTextColor">#ffffff</Color>
+    <SolidColorBrush x:Key="GHBoxActiveSelectionTextBrush" Color="{StaticResource GHBoxActiveSelectionTextColor}"
+                     PresentationOptions:Freeze="true" />
+
+    <Color x:Key="GHBoxActiveSelectionIconColor">#ffffff</Color>
+    <SolidColorBrush x:Key="GHBoxActiveSelectionIconBrush" Color="{StaticResource GHBoxActiveSelectionIconColor}"
+                     PresentationOptions:Freeze="true" />
+
+    <Color x:Key="GHBoxActiveSelectionBackgroundColor">#3998d6</Color>
+    <SolidColorBrush x:Key="GHBoxActiveSelectionBackgroundBrush" Color="{StaticResource GHBoxActiveSelectionBackgroundColor}"
+                     PresentationOptions:Freeze="true" />
+
+    <!-- Hovered (should never be used for selected or active items) -->
+    <Color x:Key="GHBoxHoverTextColor">#0a0a0a</Color>
+    <SolidColorBrush x:Key="GHBoxHoverTextBrush" Color="{StaticResource GHBoxHoverTextColor}"
+                     PresentationOptions:Freeze="true" />
+
+    <Color x:Key="GHBoxHoverIconColor">#909090</Color>
+    <SolidColorBrush x:Key="GHBoxHoverIconBrush" Color="{StaticResource GHBoxHoverIconColor}"
+                     PresentationOptions:Freeze="true" />
+
+    <Color x:Key="GHBoxHoverBackgroundColor">Transparent</Color>
+    <SolidColorBrush x:Key="GHBoxHoverBackgroundBrush" Color="{StaticResource GHBoxHoverBackgroundColor}"
+                     PresentationOptions:Freeze="true" />
 </ResourceDictionary>
\ No newline at end of file
diff --git a/src/GitHub.VisualStudio.UI/Views/Documents/IssueishCommentView.xaml b/src/GitHub.VisualStudio.UI/Views/Documents/IssueishCommentView.xaml
index 6ea85947eb..7dee441c04 100644
--- a/src/GitHub.VisualStudio.UI/Views/Documents/IssueishCommentView.xaml
+++ b/src/GitHub.VisualStudio.UI/Views/Documents/IssueishCommentView.xaml
@@ -128,39 +128,53 @@
             <Separator Grid.Column="1" Grid.ColumnSpan="2" Grid.Row="0" Margin="0 0 0 4" 
                        Background="{DynamicResource GitHubButtonBorderBrush}"/>
 
-            <ui:PromptTextBox Name="body"
-                              Grid.Column="2"
-                              Grid.Row="1"
-                              AcceptsReturn="True"
-                              AcceptsTab="True"
-                              IsReadOnly="{Binding IsReadOnly}"
-                              Margin="4 0 4 4"
-                              Text="{Binding Body, UpdateSourceTrigger=PropertyChanged}"
-                              TextWrapping="Wrap"
-                              VerticalAlignment="Center"
-                              GotFocus="ReplyPlaceholder_GotFocus"
-                              Loaded="body_Loaded"
-                              SpellCheck.IsEnabled="True">
-                <ui:PromptTextBox.Style>
-                    <Style TargetType="ui:PromptTextBox" BasedOn="{StaticResource GitHubVsPromptTextBox}">
-                        <Setter Property="Height" Value="28"/>
-                        <Setter Property="PromptText" Value="Reply..."/>
-
-                        <Style.Triggers>
-                            <DataTrigger Binding="{Binding EditState}" Value="Editing">
-                                <Setter Property="MinHeight" Value="100"/>
-                                <Setter Property="PromptText" Value="Leave a comment"/>
-                            </DataTrigger>
-                        </Style.Triggers>
-
-                        <Style.Resources>
-                            <Style TargetType="TextBlock">
-                                <Setter Property="Foreground" Value="{DynamicResource GitHubVsToolWindowText}" />
-                            </Style>
-                        </Style.Resources>
-                    </Style>
-                </ui:PromptTextBox.Style>
-            </ui:PromptTextBox>
+            <ghfvs:AutoCompleteBox
+                
+                Grid.Column="2"
+                Grid.Row="1"
+                Margin="4 0 4 4"
+                Advisor="{Binding AutoCompleteAdvisor}"
+            >
+                <ghfvs:AutoCompleteBox.ItemTemplate>
+                    <DataTemplate>
+                        <ghfvs:AutoCompleteSuggestionView ViewModel="{Binding}" />
+                    </DataTemplate>
+                </ghfvs:AutoCompleteBox.ItemTemplate>
+                <ghfvs:AutoCompleteBox.InputElement>
+                    <ghfvs:TextBoxAutoCompleteTextInput>
+                        <ui:PromptTextBox Name="body"
+                                          AcceptsReturn="True"
+                                          AcceptsTab="True"
+                                          IsReadOnly="{Binding IsReadOnly}"
+                                          Text="{Binding Body, UpdateSourceTrigger=PropertyChanged}"
+                                          TextWrapping="Wrap"
+                                          VerticalAlignment="Center"
+                                          GotFocus="ReplyPlaceholder_GotFocus"
+                                          Loaded="body_Loaded"
+                                          SpellCheck.IsEnabled="True">
+                            <ui:PromptTextBox.Style>
+                                <Style TargetType="ui:PromptTextBox" BasedOn="{StaticResource GitHubVsPromptTextBox}">
+                                    <Setter Property="Height" Value="28"/>
+                                    <Setter Property="PromptText" Value="Reply..."/>
+
+                                    <Style.Triggers>
+                                        <DataTrigger Binding="{Binding EditState}" Value="Editing">
+                                            <Setter Property="MinHeight" Value="100"/>
+                                            <Setter Property="PromptText" Value="Leave a comment"/>
+                                        </DataTrigger>
+                                    </Style.Triggers>
+
+                                    <Style.Resources>
+                                        <Style TargetType="TextBlock">
+                                            <Setter Property="Foreground" Value="{DynamicResource GitHubVsToolWindowText}" />
+                                        </Style>
+                                    </Style.Resources>
+                                </Style>
+                            </ui:PromptTextBox.Style>
+                        </ui:PromptTextBox>
+                    </ghfvs:TextBoxAutoCompleteTextInput>
+                </ghfvs:AutoCompleteBox.InputElement>
+            </ghfvs:AutoCompleteBox>
 
             <DockPanel Grid.Column="2" Grid.Row="2"
                        Margin="0 4"
diff --git a/src/GitHub.VisualStudio.UI/Views/GitHubPane/PullRequestCreationView.xaml b/src/GitHub.VisualStudio.UI/Views/GitHubPane/PullRequestCreationView.xaml
index e52b28654b..e992e56df0 100644
--- a/src/GitHub.VisualStudio.UI/Views/GitHubPane/PullRequestCreationView.xaml
+++ b/src/GitHub.VisualStudio.UI/Views/GitHubPane/PullRequestCreationView.xaml
@@ -150,18 +150,30 @@
                             SpellCheck.IsEnabled="True"
                             AutomationProperties.AutomationId="{x:Static ghfvs:AutomationIDs.PullRequestCreationTitleTextBox}"/>
 
-        <ghfvs:PromptTextBox Grid.Row="2"
-                            MinHeight="100"
-                            Margin="10,5"
-                            AcceptsReturn="True"
-                            PromptText="{x:Static ghfvs:Resources.Description}"
-                            Text="{Binding Description, UpdateSourceTrigger=PropertyChanged}"
-                            Style="{DynamicResource GitHubVsPromptTextBox}"
-                            VerticalScrollBarVisibility="Auto"
-                            TextWrapping="Wrap"
-                            SpellCheck.IsEnabled="True"
-                            AutomationProperties.AutomationId="{x:Static ghfvs:AutomationIDs.PullRequestCreationDescriptionTextBox}"/>
-        
+        <ghfvs:AutoCompleteBox
+            Grid.Row="3"
+            MinHeight="100"
+            Margin="10,5"
+            Advisor="{Binding AutoCompleteAdvisor}"
+            >
+            <ghfvs:AutoCompleteBox.ItemTemplate>
+                <DataTemplate>
+                    <ghfvs:AutoCompleteSuggestionView ViewModel="{Binding}" />
+                </DataTemplate>
+            </ghfvs:AutoCompleteBox.ItemTemplate>
+            <ghfvs:AutoCompleteBox.InputElement>
+                <ghfvs:TextBoxAutoCompleteTextInput>
+                    <ghfvs:PromptTextBox AcceptsReturn="True"
+                                         PromptText="{x:Static ghfvs:Resources.Description}"
+                                         Text="{Binding Description, UpdateSourceTrigger=PropertyChanged}"
+                                         Style="{DynamicResource GitHubVsPromptTextBox}"
+                                         VerticalScrollBarVisibility="Auto"
+                                         TextWrapping="Wrap"
+                                         SpellCheck.IsEnabled="True"/>
+                </ghfvs:TextBoxAutoCompleteTextInput>
+            </ghfvs:AutoCompleteBox.InputElement>
+        </ghfvs:AutoCompleteBox>
+
         <ghfvs:ValidationMessage x:Name="titleValidationMessage"
                                 Grid.Row="3"
                                 Fill="{StaticResource GitHubWarningBrush}"
diff --git a/src/GitHub.VisualStudio.UI/Views/GitHubPane/PullRequestReviewAuthoringView.xaml b/src/GitHub.VisualStudio.UI/Views/GitHubPane/PullRequestReviewAuthoringView.xaml
index 5e1e0797df..d59e139725 100644
--- a/src/GitHub.VisualStudio.UI/Views/GitHubPane/PullRequestReviewAuthoringView.xaml
+++ b/src/GitHub.VisualStudio.UI/Views/GitHubPane/PullRequestReviewAuthoringView.xaml
@@ -41,17 +41,30 @@
             </TextBlock>
             <TextBlock Foreground="{DynamicResource GitHubVsGrayText}" Text="{Binding PullRequestModel.Title}" TextWrapping="Wrap"/>
             <TextBlock Margin="0 12 0 4" Text="{x:Static ghfvs:Resources.YourReviewSummary}"/>
-            <TextBox AcceptsReturn="True"
-                     Background="{DynamicResource VsBrush.BrandedUIBackground}"
-                     Foreground="{DynamicResource VsBrush.BrandedUIText}"
-                     BorderBrush="{DynamicResource VsBrush.ActiveBorder}"
-                     Margin="0 4"
-                     MinHeight="120"
-                     Padding="0 4"
-                     TextWrapping="Wrap"
-                     Text="{Binding Body}"
-                     SpellCheck.IsEnabled="True"/>
             
+            <ui:AutoCompleteBox
+                    Padding="0 4"
+                    Margin="0 4"
+                    Advisor="{Binding AutoCompleteAdvisor}">
+                <ui:AutoCompleteBox.ItemTemplate>
+                    <DataTemplate>
+                        <ui:AutoCompleteSuggestionView ViewModel="{Binding}" />
+                    </DataTemplate>
+                </ui:AutoCompleteBox.ItemTemplate>
+                <ui:AutoCompleteBox.InputElement>
+                    <ui:TextBoxAutoCompleteTextInput>
+                        <TextBox AcceptsReturn="True"
+                                 Background="{DynamicResource VsBrush.BrandedUIBackground}"
+                                 Foreground="{DynamicResource VsBrush.BrandedUIText}"
+                                 BorderBrush="{DynamicResource VsBrush.ActiveBorder}"
+                                 MinHeight="120"
+                                 TextWrapping="Wrap"
+                                 Text="{Binding Body}"
+                                 SpellCheck.IsEnabled="True"/>
+                    </ui:TextBoxAutoCompleteTextInput>
+                </ui:AutoCompleteBox.InputElement>
+            </ui:AutoCompleteBox>
+
             <StackPanel Margin="0 4" Orientation="Horizontal">
                 <ui:DropDownButton AutoCloseOnClick="True" Foreground="{DynamicResource GHBlueLinkButtonTextBrush}">
                     <ui:GitHubActionLink>Submit review</ui:GitHubActionLink>
diff --git a/src/GitHub.VisualStudio.UI/Views/PullRequestReviewCommentView.xaml b/src/GitHub.VisualStudio.UI/Views/PullRequestReviewCommentView.xaml
index 41597a44dc..eab0a78381 100644
--- a/src/GitHub.VisualStudio.UI/Views/PullRequestReviewCommentView.xaml
+++ b/src/GitHub.VisualStudio.UI/Views/PullRequestReviewCommentView.xaml
@@ -161,39 +161,51 @@
             <Separator Grid.Column="0" Grid.ColumnSpan="2" Grid.Row="0" Margin="0 0 0 4" 
                        Background="{DynamicResource GitHubButtonBorderBrush}"/>
 
-            <ui:PromptTextBox Name="body"
-                              Grid.Column="1"
-                              Grid.Row="1"
-                              AcceptsReturn="True"
-                              AcceptsTab="True"
-                              IsReadOnly="{Binding IsReadOnly}"
-                              Margin="4 0 4 4"
-                              Text="{Binding Body, UpdateSourceTrigger=PropertyChanged}"
-                              TextWrapping="Wrap"
-                              VerticalAlignment="Center"
-                              GotFocus="ReplyPlaceholder_GotFocus"
-                              Loaded="body_Loaded"
-                              SpellCheck.IsEnabled="True">
-                <ui:PromptTextBox.Style>
-                    <Style TargetType="ui:PromptTextBox" BasedOn="{StaticResource GitHubVsPromptTextBox}">
-                        <Setter Property="Height" Value="28"/>
-                        <Setter Property="PromptText" Value="Reply..."/>
+            <ui:AutoCompleteBox
+                Grid.Column="1"
+                Grid.Row="1"
+                Margin="4 0 4 4"
+                Advisor="{Binding AutoCompleteAdvisor}">
+                <ui:AutoCompleteBox.ItemTemplate>
+                    <DataTemplate>
+                        <ui:AutoCompleteSuggestionView ViewModel="{Binding}" />
+                    </DataTemplate>
+                </ui:AutoCompleteBox.ItemTemplate>
+                <ui:AutoCompleteBox.InputElement>
+                    <ui:TextBoxAutoCompleteTextInput>
+                        <ui:PromptTextBox Name="body"
+                                          AcceptsReturn="True"
+                                          AcceptsTab="True"
+                                          IsReadOnly="{Binding IsReadOnly}"
+                                          Text="{Binding Body, UpdateSourceTrigger=PropertyChanged}"
+                                          TextWrapping="Wrap"
+                                          VerticalAlignment="Center"
+                                          GotFocus="ReplyPlaceholder_GotFocus"
+                                          Loaded="body_Loaded"
+                                          SpellCheck.IsEnabled="True">
+                            <ui:PromptTextBox.Style>
+                                <Style TargetType="ui:PromptTextBox" BasedOn="{StaticResource GitHubVsPromptTextBox}">
+                                    <Setter Property="Height" Value="28"/>
+                                    <Setter Property="PromptText" Value="Reply..."/>
 
-                        <Style.Triggers>
-                            <DataTrigger Binding="{Binding EditState}" Value="Editing">
-                                <Setter Property="MinHeight" Value="100"/>
-                                <Setter Property="PromptText" Value="Leave a comment"/>
-                            </DataTrigger>
-                        </Style.Triggers>
+                                    <Style.Triggers>
+                                        <DataTrigger Binding="{Binding EditState}" Value="Editing">
+                                            <Setter Property="MinHeight" Value="100"/>
+                                            <Setter Property="PromptText" Value="Leave a comment"/>
+                                        </DataTrigger>
+                                    </Style.Triggers>
 
-                        <Style.Resources>
-                            <Style TargetType="TextBlock">
-                                <Setter Property="Foreground" Value="{DynamicResource GitHubVsToolWindowText}" />
-                            </Style>
-                        </Style.Resources>
-                    </Style>
-                </ui:PromptTextBox.Style>
-            </ui:PromptTextBox>
+                                    <Style.Resources>
+                                        <Style TargetType="TextBlock">
+                                            <Setter Property="Foreground" Value="{DynamicResource GitHubVsToolWindowText}" />
+                                        </Style>
+                                    </Style.Resources>
+                                </Style>
+                            </ui:PromptTextBox.Style>
+                        </ui:PromptTextBox>
+                    </ui:TextBoxAutoCompleteTextInput>
+                </ui:AutoCompleteBox.InputElement>
+            </ui:AutoCompleteBox>
 
             <DockPanel Grid.Column="1" Grid.Row="2"
                        Margin="0 4"
diff --git a/test/GitHub.App.UnitTests/ViewModels/CommentThreadViewModelTests.cs b/test/GitHub.App.UnitTests/ViewModels/CommentThreadViewModelTests.cs
index 41744b5780..562522d252 100644
--- a/test/GitHub.App.UnitTests/ViewModels/CommentThreadViewModelTests.cs
+++ b/test/GitHub.App.UnitTests/ViewModels/CommentThreadViewModelTests.cs
@@ -113,7 +113,7 @@ public async Task AddPlaceholder(bool isEditing)
         class TestComment : CommentViewModel
         {
             public TestComment()
-                : base(Substitute.For<ICommentService>())
+                : base(Substitute.For<ICommentService>(), Substitute.For<IAutoCompleteAdvisor>())
             {
             }
 
diff --git a/test/GitHub.App.UnitTests/ViewModels/CommentViewModelTests.cs b/test/GitHub.App.UnitTests/ViewModels/CommentViewModelTests.cs
index 6fa4e42632..786719d517 100644
--- a/test/GitHub.App.UnitTests/ViewModels/CommentViewModelTests.cs
+++ b/test/GitHub.App.UnitTests/ViewModels/CommentViewModelTests.cs
@@ -65,11 +65,14 @@ await target.InitializeAsync(
         }
 
         CommentViewModel CreateTarget(
-            ICommentService commentService = null)
+            ICommentService commentService = null,
+            IAutoCompleteAdvisor autoCompleteAdvisor = null
+            )
         {
             commentService = commentService ?? Substitute.For<ICommentService>();
+            autoCompleteAdvisor = autoCompleteAdvisor ?? Substitute.For<IAutoCompleteAdvisor>();
 
-            return new CommentViewModel(commentService);
+            return new CommentViewModel(commentService, autoCompleteAdvisor);
         }
     }
 }
diff --git a/test/GitHub.App.UnitTests/ViewModels/Documents/IssueishCommentViewModelTests.cs b/test/GitHub.App.UnitTests/ViewModels/Documents/IssueishCommentViewModelTests.cs
index f925182bee..cee68ba3d5 100644
--- a/test/GitHub.App.UnitTests/ViewModels/Documents/IssueishCommentViewModelTests.cs
+++ b/test/GitHub.App.UnitTests/ViewModels/Documents/IssueishCommentViewModelTests.cs
@@ -54,11 +54,13 @@ await target.InitializeAsync(
         }
 
         IssueishCommentViewModel CreateTarget(
-            ICommentService commentService = null)
+            ICommentService commentService = null,
+            IAutoCompleteAdvisor autoCompleteAdvisor = null)
         {
             commentService = commentService ?? Substitute.For<ICommentService>();
+            autoCompleteAdvisor = autoCompleteAdvisor ?? Substitute.For<IAutoCompleteAdvisor>();
 
-            return new IssueishCommentViewModel(commentService);
+            return new IssueishCommentViewModel(commentService, autoCompleteAdvisor);
         }
     }
 }
diff --git a/test/GitHub.App.UnitTests/ViewModels/GitHubPane/PullRequestCreationViewModelTests.cs b/test/GitHub.App.UnitTests/ViewModels/GitHubPane/PullRequestCreationViewModelTests.cs
index 4e8d1ca8b6..2c2df0a648 100644
--- a/test/GitHub.App.UnitTests/ViewModels/GitHubPane/PullRequestCreationViewModelTests.cs
+++ b/test/GitHub.App.UnitTests/ViewModels/GitHubPane/PullRequestCreationViewModelTests.cs
@@ -55,6 +55,7 @@ struct TestData
         public IConnection Connection;
         public IApiClient ApiClient;
         public IModelService ModelService;
+        public IAutoCompleteAdvisor AutoCompleteAdvisor { get; set; }
 
         public IModelServiceFactory GetModelServiceFactory()
         {
@@ -78,6 +79,7 @@ static TestData PrepareTestData(
         var connection = Substitute.For<IConnection>();
         var api = Substitute.For<IApiClient>();
         var ms = Substitute.For<IModelService>();
+        var autoCompleteAdvisor = Substitute.For<IAutoCompleteAdvisor>();
 
         connection.HostAddress.Returns(HostAddress.Create("https://github.com"));
 
@@ -121,7 +123,8 @@ static TestData PrepareTestData(
             NotificationService = notifications,
             Connection = connection,
             ApiClient = api,
-            ModelService = ms
+            ModelService = ms,
+            AutoCompleteAdvisor = autoCompleteAdvisor
         };
     }
 
@@ -147,7 +150,7 @@ public async Task TargetBranchDisplayNameIncludesRepoOwnerWhenForkAsync()
         var prservice = new PullRequestService(data.GitClient, data.GitService, Substitute.For<IVSGitExt>(), Substitute.For<IApiClientFactory>(), Substitute.For<IGraphQLClientFactory>(), data.ServiceProvider.GetOperatingSystem(), Substitute.For<IUsageTracker>());
         prservice.GetPullRequestTemplate(data.ActiveRepo).Returns(Observable.Empty<string>());
         var vm = new PullRequestCreationViewModel(data.GetModelServiceFactory(), prservice, data.NotificationService,
-            Substitute.For<IMessageDraftStore>(), data.GitService);
+            Substitute.For<IMessageDraftStore>(), data.GitService, data.AutoCompleteAdvisor);
         await vm.InitializeAsync(data.ActiveRepo, data.Connection);
         Assert.That("octokit/master", Is.EqualTo(vm.TargetBranch.DisplayName));
     }
@@ -183,7 +186,7 @@ public async Task CreatingPRsAsync(
 
         var prservice = new PullRequestService(data.GitClient, data.GitService, Substitute.For<IVSGitExt>(), Substitute.For<IApiClientFactory>(), Substitute.For<IGraphQLClientFactory>(), data.ServiceProvider.GetOperatingSystem(), Substitute.For<IUsageTracker>());
         var vm = new PullRequestCreationViewModel(data.GetModelServiceFactory(), prservice, data.NotificationService,
-            Substitute.For<IMessageDraftStore>(), data.GitService);
+            Substitute.For<IMessageDraftStore>(), data.GitService, data.AutoCompleteAdvisor);
         await vm.InitializeAsync(data.ActiveRepo, data.Connection);
 
         // the TargetBranch property gets set to whatever the repo default is (we assume master here),
@@ -226,7 +229,7 @@ public async Task TemplateIsUsedIfPresentAsync()
         prservice.GetPullRequestTemplate(data.ActiveRepo).Returns(Observable.Return("Test PR template"));
 
         var vm = new PullRequestCreationViewModel(data.GetModelServiceFactory(), prservice, data.NotificationService,
-            Substitute.For<IMessageDraftStore>(), data.GitService);
+            Substitute.For<IMessageDraftStore>(), data.GitService, data.AutoCompleteAdvisor);
         await vm.InitializeAsync(data.ActiveRepo, data.Connection);
 
         Assert.That("Test PR template", Is.EqualTo(vm.Description));
@@ -246,7 +249,7 @@ public async Task LoadsDraft()
 
         var prservice = Substitute.For<IPullRequestService>();
         var vm = new PullRequestCreationViewModel(data.GetModelServiceFactory(), prservice, data.NotificationService,
-            draftStore, data.GitService);
+            draftStore, data.GitService, data.AutoCompleteAdvisor);
         await vm.InitializeAsync(data.ActiveRepo, data.Connection);
 
         Assert.That(vm.PRTitle, Is.EqualTo("This is a Title."));
@@ -261,7 +264,7 @@ public async Task UpdatesDraftWhenDescriptionChanges()
         var draftStore = Substitute.For<IMessageDraftStore>();
         var prservice = Substitute.For<IPullRequestService>();
         var vm = new PullRequestCreationViewModel(data.GetModelServiceFactory(), prservice, data.NotificationService,
-            draftStore, data.GitService, scheduler);
+            draftStore, data.GitService, data.AutoCompleteAdvisor, scheduler);
         await vm.InitializeAsync(data.ActiveRepo, data.Connection);
 
         vm.Description = "Body changed.";
@@ -284,7 +287,7 @@ public async Task UpdatesDraftWhenTitleChanges()
         var draftStore = Substitute.For<IMessageDraftStore>();
         var prservice = Substitute.For<IPullRequestService>();
         var vm = new PullRequestCreationViewModel(data.GetModelServiceFactory(), prservice, data.NotificationService,
-            draftStore, data.GitService, scheduler);
+            draftStore, data.GitService, data.AutoCompleteAdvisor, scheduler);
         await vm.InitializeAsync(data.ActiveRepo, data.Connection);
 
         vm.PRTitle = "Title changed.";
@@ -307,7 +310,7 @@ public async Task DeletesDraftWhenPullRequestSubmitted()
         var draftStore = Substitute.For<IMessageDraftStore>();
         var prservice = Substitute.For<IPullRequestService>();
         var vm = new PullRequestCreationViewModel(data.GetModelServiceFactory(), prservice, data.NotificationService, draftStore,
-            data.GitService, scheduler);
+            data.GitService, data.AutoCompleteAdvisor, scheduler);
         await vm.InitializeAsync(data.ActiveRepo, data.Connection);
 
         await vm.CreatePullRequest.Execute();
@@ -323,7 +326,7 @@ public async Task DeletesDraftWhenCanceled()
         var draftStore = Substitute.For<IMessageDraftStore>();
         var prservice = Substitute.For<IPullRequestService>();
         var vm = new PullRequestCreationViewModel(data.GetModelServiceFactory(), prservice, data.NotificationService, draftStore,
-            data.GitService, scheduler);
+            data.GitService, data.AutoCompleteAdvisor, scheduler);
         await vm.InitializeAsync(data.ActiveRepo, data.Connection);
 
         await vm.Cancel.Execute();
diff --git a/test/GitHub.App.UnitTests/ViewModels/GitHubPane/PullRequestReviewAuthoringViewModelTests.cs b/test/GitHub.App.UnitTests/ViewModels/GitHubPane/PullRequestReviewAuthoringViewModelTests.cs
index 42c876cb35..f2d4d2925a 100644
--- a/test/GitHub.App.UnitTests/ViewModels/GitHubPane/PullRequestReviewAuthoringViewModelTests.cs
+++ b/test/GitHub.App.UnitTests/ViewModels/GitHubPane/PullRequestReviewAuthoringViewModelTests.cs
@@ -487,12 +487,15 @@ static PullRequestReviewAuthoringViewModel CreateTarget(
             IPullRequestSessionManager sessionManager = null,
             IMessageDraftStore draftStore = null,
             IPullRequestFilesViewModel files = null,
-            IScheduler timerScheduler = null)
+            IScheduler timerScheduler = null,
+            IAutoCompleteAdvisor autoCompleteAdvisor = null
+            )
         {
             editorService = editorService ?? Substitute.For<IPullRequestEditorService>();
             sessionManager = sessionManager ?? CreateSessionManager();
             draftStore = draftStore ?? Substitute.For<IMessageDraftStore>();
             files = files ?? Substitute.For<IPullRequestFilesViewModel>();
+            autoCompleteAdvisor = autoCompleteAdvisor ?? Substitute.For<IAutoCompleteAdvisor>();
             timerScheduler = timerScheduler ?? DefaultScheduler.Instance;
 
             return new PullRequestReviewAuthoringViewModel(
@@ -501,6 +504,7 @@ static PullRequestReviewAuthoringViewModel CreateTarget(
                 sessionManager,
                 draftStore,
                 files,
+                autoCompleteAdvisor,
                 timerScheduler);
         }
 
diff --git a/test/GitHub.App.UnitTests/ViewModels/PullRequestReviewCommentThreadViewModelTests.cs b/test/GitHub.App.UnitTests/ViewModels/PullRequestReviewCommentThreadViewModelTests.cs
index 72e2c88536..2420120dea 100644
--- a/test/GitHub.App.UnitTests/ViewModels/PullRequestReviewCommentThreadViewModelTests.cs
+++ b/test/GitHub.App.UnitTests/ViewModels/PullRequestReviewCommentThreadViewModelTests.cs
@@ -172,8 +172,9 @@ static IViewViewModelFactory CreateFactory()
         {
             var result = Substitute.For<IViewViewModelFactory>();
             var commentService = Substitute.For<ICommentService>();
+            var autoCompleteAdvisor = Substitute.For<IAutoCompleteAdvisor>();
             result.CreateViewModel<IPullRequestReviewCommentViewModel>().Returns(_ =>
-                new PullRequestReviewCommentViewModel(commentService));
+                new PullRequestReviewCommentViewModel(commentService, autoCompleteAdvisor));
             return result;
         }
 
diff --git a/test/GitHub.App.UnitTests/ViewModels/PullRequestReviewCommentViewModelTests.cs b/test/GitHub.App.UnitTests/ViewModels/PullRequestReviewCommentViewModelTests.cs
index 838d6fc8ca..d6d2fe8043 100644
--- a/test/GitHub.App.UnitTests/ViewModels/PullRequestReviewCommentViewModelTests.cs
+++ b/test/GitHub.App.UnitTests/ViewModels/PullRequestReviewCommentViewModelTests.cs
@@ -54,7 +54,8 @@ public async Task CanBeExecutedForPlaceholders()
                 var thread = CreateThread();
                 var currentUser = Substitute.For<IActorViewModel>();
                 var commentService = Substitute.For<ICommentService>();
-                var target = new PullRequestReviewCommentViewModel(commentService);
+                var autoCompleteAdvisor = Substitute.For<IAutoCompleteAdvisor>();
+                var target = new PullRequestReviewCommentViewModel(commentService, autoCompleteAdvisor);
 
                 await target.InitializeAsPlaceholderAsync(session, thread, false, false);
 
@@ -98,7 +99,8 @@ public async Task CannotBeExecutedForPlaceholders()
                 var thread = CreateThread();
                 var currentUser = Substitute.For<IActorViewModel>();
                 var commentService = Substitute.For<ICommentService>();
-                var target = new PullRequestReviewCommentViewModel(commentService);
+                var autoCompleteAdvisor = Substitute.For<IAutoCompleteAdvisor>();
+                var target = new PullRequestReviewCommentViewModel(commentService, autoCompleteAdvisor);
 
                 await target.InitializeAsPlaceholderAsync(session, thread, false, false);
 
@@ -218,16 +220,18 @@ static async Task<PullRequestReviewCommentViewModel> CreateTarget(
             ICommentThreadViewModel thread = null,
             ActorModel currentUser = null,
             PullRequestReviewModel review = null,
-            PullRequestReviewCommentModel comment = null)
+            PullRequestReviewCommentModel comment = null,
+            IAutoCompleteAdvisor autoCompleteAdvisor = null)
         {
             session = session ?? CreateSession();
             commentService = commentService ?? Substitute.For<ICommentService>();
+            autoCompleteAdvisor = autoCompleteAdvisor ?? Substitute.For<IAutoCompleteAdvisor>();
             thread = thread ?? CreateThread();
             currentUser = currentUser ?? new ActorModel { Login = "CurrentUser" };
             comment = comment ?? new PullRequestReviewCommentModel();
             review = review ?? CreateReview(PullRequestReviewState.Approved, comment);
 
-            var result = new PullRequestReviewCommentViewModel(commentService);
+            var result = new PullRequestReviewCommentViewModel(commentService, autoCompleteAdvisor);
             await result.InitializeAsync(session, thread, review, comment, CommentEditState.None);
             return result;
         }
diff --git a/test/GitHub.InlineReviews.UnitTests/ViewModels/InlineCommentPeekViewModelTests.cs b/test/GitHub.InlineReviews.UnitTests/ViewModels/InlineCommentPeekViewModelTests.cs
index bbdf4668c2..5e9ac069e6 100644
--- a/test/GitHub.InlineReviews.UnitTests/ViewModels/InlineCommentPeekViewModelTests.cs
+++ b/test/GitHub.InlineReviews.UnitTests/ViewModels/InlineCommentPeekViewModelTests.cs
@@ -272,8 +272,9 @@ static IViewViewModelFactory CreateFactory()
             var draftStore = Substitute.For<IMessageDraftStore>();
             var commentService = Substitute.For<ICommentService>();
             var result = Substitute.For<IViewViewModelFactory>();
+            var autoCompleteAdvisor = Substitute.For<IAutoCompleteAdvisor>();
             result.CreateViewModel<IPullRequestReviewCommentViewModel>().Returns(_ =>
-                new PullRequestReviewCommentViewModel(commentService));
+                new PullRequestReviewCommentViewModel(commentService, autoCompleteAdvisor));
             result.CreateViewModel<IPullRequestReviewCommentThreadViewModel>().Returns(_ =>
                 new PullRequestReviewCommentThreadViewModel(draftStore, result));
             return result;
diff --git a/test/GitHub.UI.UnitTests/Controls/AutoCompleteBoxTests.cs b/test/GitHub.UI.UnitTests/Controls/AutoCompleteBoxTests.cs
index ace2f2b467..33baca44a3 100644
--- a/test/GitHub.UI.UnitTests/Controls/AutoCompleteBoxTests.cs
+++ b/test/GitHub.UI.UnitTests/Controls/AutoCompleteBoxTests.cs
@@ -1,212 +1,293 @@
 using System.Collections.Generic;
 using System.Collections.ObjectModel;
+using System.Linq;
 using System.Reactive.Linq;
+using System.Threading;
+using System.Windows;
 using System.Windows.Controls;
 using System.Windows.Input;
 using System.Windows.Media.Imaging;
-using GitHub.Tests.TestHelpers;
-using GitHub.UI;
+using GitHub.Extensions;
+using GitHub.Models;
+using GitHub.Services;
 using GitHub.UI.Helpers;
-using Moq;
-using Xunit;
+using NSubstitute;
+using NUnit.Framework;
 
-public class AutoCompleteBoxTests
+namespace GitHub.UI.UnitTests.Controls
 {
-    public class TheItemsSourceProperty
+    public class AutoCompleteBoxTests
     {
-        [STAFact]
-        public void SelectsFirstItemWhenSetToNonEmptyCollection()
+        [Apartment(ApartmentState.STA)]
+        public class TheItemsSourceProperty
         {
-            var obs = Observable.Return(new BitmapImage());
-
-            var suggestions = new List<AutoCompleteSuggestion>
-            {
-                new AutoCompleteSuggestion("aaaa", obs, ":", ":"),
-                new AutoCompleteSuggestion("bbbb", obs, ":", ":"),
-                new AutoCompleteSuggestion("ccc", obs, ":", ":")
-            };
-            var result = new AutoCompleteResult(1, new ReadOnlyCollection<AutoCompleteSuggestion>(suggestions));
-            var advisor = Mock.Of<IAutoCompleteAdvisor>(
-                a => a.GetAutoCompletionSuggestions(Args.String, Args.Int32) == Observable.Return(result));
-            var textBox = new TextBox();
-            var autoCompleteBox = new AutoCompleteBox(Mock.Of<IDpiManager>())
+            [Test]
+            public void SelectsFirstItemWhenSetToNonEmptyCollection()
             {
-                SelectionAdapter = new SelectorSelectionAdapter(new ListBox()),
-                Advisor = advisor,
-                TextBox = new TextBoxAutoCompleteTextInput { TextBox = textBox }
-            };
+                var obs = Observable.Return(new BitmapImage());
+
+                var suggestions = new List<AutoCompleteSuggestion>
+                {
+                    new AutoCompleteSuggestion("aaaa", obs, ":", ":"),
+                    new AutoCompleteSuggestion("bbbb", obs, ":", ":"),
+                    new AutoCompleteSuggestion("ccc", obs, ":", ":")
+                };
+                var result = new AutoCompleteResult(1, new ReadOnlyCollection<AutoCompleteSuggestion>(suggestions));
+                var advisor = Substitute.For<IAutoCompleteAdvisor>();
+                advisor.GetAutoCompletionSuggestions(Arg.Any<string>(), Arg.Any<int>())
+                    .Returns(Observable.Return(result));
+
+                var textBox = new TextBox();
+                var autoCompleteBox = new AutoCompleteBox(Substitute.For<IDpiManager>())
+                {
+                    SelectionAdapter = new SelectorSelectionAdapter(new ListBox()),
+                    Advisor = advisor,
+                    TextBox = new TextBoxAutoCompleteTextInput { TextBox = textBox }
+                };
 
-            textBox.Text = ":";
+                textBox.Text = ":";
 
-            Assert.Equal("aaaa", ((AutoCompleteSuggestion) autoCompleteBox.SelectedItem).Name);
-            Assert.Equal(":", autoCompleteBox.Text); // It should not have expanded it yet
+                Assert.That(((AutoCompleteSuggestion)autoCompleteBox.SelectedItem).Name, Is.EqualTo("aaaa"));
+                Assert.That(autoCompleteBox.Text, Is.EqualTo(":"));
+            }
         }
-    }
 
-    public class TheIsDropDownOpenProperty
-    {
-        [STAFact]
-        public void IsTrueWhenTextBoxChangesWithPrefixedValue()
+        [Apartment(ApartmentState.STA)]
+        public class TheIsDropDownOpenProperty
         {
-            var obs = Observable.Return(new BitmapImage());
+            [Test]
+            public void IsTrueWhenTextBoxChangesWithPrefixedValue()
+            {
+                var obs = Observable.Return(new BitmapImage());
+
+                var suggestions = new List<AutoCompleteSuggestion>
+                {
+                    new AutoCompleteSuggestion("aaaa", obs, ":", ":"),
+                    new AutoCompleteSuggestion("bbbb", obs, ":", ":"),
+                    new AutoCompleteSuggestion("ccc", obs, ":", ":")
+                };
+                var result = new AutoCompleteResult(0, new ReadOnlyCollection<AutoCompleteSuggestion>(suggestions));
+                var advisor = Substitute.For<IAutoCompleteAdvisor>();
+                advisor.GetAutoCompletionSuggestions(Arg.Any<string>(), Arg.Any<int>())
+                    .Returns(Observable.Return(result));
+
+                var textBox = new TextBox();
+                var autoCompleteBox = new AutoCompleteBox(Substitute.For<IDpiManager>())
+                {
+                    SelectionAdapter = new SelectorSelectionAdapter(new ListBox()),
+                    Advisor = advisor,
+                    TextBox = new TextBoxAutoCompleteTextInput { TextBox = textBox }
+                };
+
+                textBox.Text = ":";
+
+                Assert.True(autoCompleteBox.IsDropDownOpen);
+            }
 
-            var suggestions = new List<AutoCompleteSuggestion>
+            [Test]
+            public void IsFalseAfterASuggestionIsSelected()
             {
-                new AutoCompleteSuggestion("aaaa", obs, ":", ":"),
-                new AutoCompleteSuggestion("bbbb", obs, ":", ":"),
-                new AutoCompleteSuggestion("ccc", obs, ":", ":")
-            };
-            var result = new AutoCompleteResult(0, new ReadOnlyCollection<AutoCompleteSuggestion>(suggestions));
-            var advisor = Mock.Of<IAutoCompleteAdvisor>(
-                a => a.GetAutoCompletionSuggestions(Args.String, Args.Int32) == Observable.Return(result));
-            var textBox = new TextBox();
-            var autoCompleteBox = new AutoCompleteBox(Mock.Of<IDpiManager>())
+                var obs = Observable.Return(new BitmapImage());
+
+                var suggestions = new List<AutoCompleteSuggestion>
+                {
+                    new AutoCompleteSuggestion("aaaa", obs, ":", ":"),
+                    new AutoCompleteSuggestion("bbbb", obs, ":", ":"),
+                    new AutoCompleteSuggestion("ccc", obs, ":", ":")
+                };
+                var result = new AutoCompleteResult(2, new ReadOnlyCollection<AutoCompleteSuggestion>(suggestions));
+                var advisor = Substitute.For<IAutoCompleteAdvisor>();
+                advisor.GetAutoCompletionSuggestions(Arg.Any<string>(), Arg.Any<int>())
+                    .Returns(Observable.Return(result));
+
+                var selectionAdapter = new TestSelectorSelectionAdapter();
+                var textBox = new TextBox();
+                var autoCompleteBox = new AutoCompleteBox(Substitute.For<IDpiManager>())
+                {
+                    SelectionAdapter = selectionAdapter,
+                    Advisor = advisor,
+                    TextBox = new TextBoxAutoCompleteTextInput {TextBox = textBox}
+                };
+                textBox.Text = "A :a";
+                textBox.CaretIndex = 4;
+                Assert.AreEqual(4, textBox.CaretIndex);
+                Assert.AreEqual(4, autoCompleteBox.TextBox.CaretIndex);
+                Assert.True(autoCompleteBox.IsDropDownOpen);
+
+                selectionAdapter.DoCommit();
+
+                Assert.That(textBox.Text, Is.EqualTo("A :aaaa: "));
+                Assert.False(autoCompleteBox.IsDropDownOpen);
+            }
+
+            [Test]
+            public void IsFalseAfterASuggestionIsCancelled()
             {
-                SelectionAdapter = new SelectorSelectionAdapter(new ListBox()),
-                Advisor = advisor,
-                TextBox = new TextBoxAutoCompleteTextInput { TextBox = textBox }
-            };
+                var obs = Observable.Return(new BitmapImage());
 
-            textBox.Text = ":";
+                var suggestions = new List<AutoCompleteSuggestion>
+                {
+                    new AutoCompleteSuggestion("aaaa", obs, ":", ":"),
+                    new AutoCompleteSuggestion("bbbb", obs, ":", ":"),
+                    new AutoCompleteSuggestion("ccc", obs, ":", ":")
+                };
+                var result = new AutoCompleteResult(2, new ReadOnlyCollection<AutoCompleteSuggestion>(suggestions));
+                var advisor = Substitute.For<IAutoCompleteAdvisor>();
+                advisor.GetAutoCompletionSuggestions(Arg.Any<string>(), Arg.Any<int>())
+                    .Returns(Observable.Return(result));
 
-            Assert.True(autoCompleteBox.IsDropDownOpen);
-        }
+                var selectionAdapter = new TestSelectorSelectionAdapter();
+                var textBox = new TextBox();
+                var autoCompleteBox = new AutoCompleteBox(Substitute.For<IDpiManager>())
+                {
+                    SelectionAdapter = selectionAdapter,
+                    Advisor = advisor,
+                    TextBox = new TextBoxAutoCompleteTextInput { TextBox = textBox }
+                };
+                textBox.Text = "A :a";
+                textBox.CaretIndex = 4;
+                Assert.AreEqual(4, textBox.CaretIndex);
+                Assert.AreEqual(4, autoCompleteBox.TextBox.CaretIndex);
+                Assert.True(autoCompleteBox.IsDropDownOpen);
 
-        [STAFact]
-        public void IsFalseAfterASuggestionIsSelected()
-        {
-            var obs = Observable.Return(new BitmapImage());
+                selectionAdapter.DoCancel();
+
+                Assert.That(textBox.Text, Is.EqualTo("A :a"));
+                Assert.False(autoCompleteBox.IsDropDownOpen);
+            }
 
-            var suggestions = new List<AutoCompleteSuggestion>
+            [Test]
+            public void HandlesKeyPressesToSelectAndCancelSelections()
             {
-                new AutoCompleteSuggestion("aaaa", obs, ":", ":"),
-                new AutoCompleteSuggestion("bbbb", obs, ":", ":"),
-                new AutoCompleteSuggestion("ccc", obs, ":", ":")
-            };
-            var result = new AutoCompleteResult(2, new ReadOnlyCollection<AutoCompleteSuggestion>(suggestions));
-            var advisor = Mock.Of<IAutoCompleteAdvisor>(
-                a => a.GetAutoCompletionSuggestions(Args.String, Args.Int32) == Observable.Return(result));
-            var selectionAdapter = new TestSelectorSelectionAdapter();
-            var textBox = new TextBox();
-            var autoCompleteBox = new AutoCompleteBox(Mock.Of<IDpiManager>())
+                var obs = Observable.Return(new BitmapImage());
+
+                var suggestions = new List<AutoCompleteSuggestion>
+                {
+                    new AutoCompleteSuggestion("aaaa", obs, ":", ":"),
+                    new AutoCompleteSuggestion("bbbb", obs, ":", ":"),
+                    new AutoCompleteSuggestion("ccc", obs, ":", ":")
+                };
+                var result = new AutoCompleteResult(2, new ReadOnlyCollection<AutoCompleteSuggestion>(suggestions));
+                var advisor = Substitute.For<IAutoCompleteAdvisor>();
+                advisor.GetAutoCompletionSuggestions(Arg.Any<string>(), Arg.Any<int>())
+                    .Returns(Observable.Return(result));
+
+                var selectionAdapter = new TestSelectorSelectionAdapter();
+                var textBox = new TextBox();
+                var autoCompleteBox = new AutoCompleteBox(Substitute.For<IDpiManager>())
+                {
+                    SelectionAdapter = selectionAdapter,
+                    Advisor = advisor,
+                    TextBox = new TextBoxAutoCompleteTextInput { TextBox = textBox }
+                };
+                textBox.Text = "A :a";
+                textBox.CaretIndex = 4;
+                Assert.AreEqual(4, textBox.CaretIndex);
+                Assert.AreEqual(4, autoCompleteBox.TextBox.CaretIndex);
+                Assert.True(autoCompleteBox.IsDropDownOpen);
+                selectionAdapter.SelectorControl.SelectedIndex = 1; // Select the second item
+
+                selectionAdapter.DoKeyDown(Key.Enter);
+
+                Assert.AreEqual("A :bbbb: ", textBox.Text);
+                Assert.False(autoCompleteBox.IsDropDownOpen);
+
+                textBox.Text = "A :bbbb: :";
+                textBox.CaretIndex = 10;
+
+                // Ensure we can re-open the dropdown
+                Assert.True(autoCompleteBox.IsDropDownOpen);
+
+                selectionAdapter.DoKeyDown(Key.Escape);
+                Assert.False(autoCompleteBox.IsDropDownOpen);
+                Assert.AreEqual("A :bbbb: :", textBox.Text);
+            }
+
+            class TestSelectorSelectionAdapter : SelectorSelectionAdapter
             {
-                SelectionAdapter = selectionAdapter,
-                Advisor = advisor,
-                TextBox = new TextBoxAutoCompleteTextInput {TextBox = textBox}
-            };
-            textBox.Text = "A :a";
-            textBox.CaretIndex = 4;
-            Assert.Equal(4, textBox.CaretIndex);
-            Assert.Equal(4, autoCompleteBox.TextBox.CaretIndex);
-            Assert.True(autoCompleteBox.IsDropDownOpen);
-
-            selectionAdapter.DoCommit();
-
-            Assert.Equal("A :aaaa: ", textBox.Text);
-            Assert.False(autoCompleteBox.IsDropDownOpen);
+                public TestSelectorSelectionAdapter()
+                    : base(new ListBox())
+                {
+                }
+
+                public void DoCommit()
+                {
+                    base.OnCommit();
+                }
+
+                public void DoCancel()
+                {
+                    base.OnCancel();
+                }
+
+                public void DoKeyDown(Key key)
+                {
+                    var keyEventArgs = FakeKeyEventArgs.Create(key, false);
+                    HandleKeyDown(keyEventArgs);
+                }
+            }
         }
 
-        [STAFact]
-        public void IsFalseAfterASuggestionIsCancelled()
+        public class FakeKeyEventArgs : KeyEventArgs
         {
-            var obs = Observable.Return(new BitmapImage());
+            public static KeyEventArgs Create(Key realKey, bool isSystemKey, params Key[] pressedKeys)
+            {
+                return new FakeKeyEventArgs(realKey, isSystemKey, GetKeyStatesFromPressedKeys(pressedKeys));
+            }
 
-            var suggestions = new List<AutoCompleteSuggestion>
+            public static KeyEventArgs Create(Key realKey, params Key[] pressedKeys)
             {
-                new AutoCompleteSuggestion("aaaa", obs, ":", ":"),
-                new AutoCompleteSuggestion("bbbb", obs, ":", ":"),
-                new AutoCompleteSuggestion("ccc", obs, ":", ":")
-            };
-            var result = new AutoCompleteResult(2, new ReadOnlyCollection<AutoCompleteSuggestion>(suggestions));
-            var advisor = Mock.Of<IAutoCompleteAdvisor>(
-                a => a.GetAutoCompletionSuggestions(Args.String, Args.Int32) == Observable.Return(result));
-            var selectionAdapter = new TestSelectorSelectionAdapter();
-            var textBox = new TextBox();
-            var autoCompleteBox = new AutoCompleteBox(Mock.Of<IDpiManager>())
+                return new FakeKeyEventArgs(realKey, false, GetKeyStatesFromPressedKeys(pressedKeys));
+            }
+
+            FakeKeyEventArgs(Key realKey, bool isSystemKey, IDictionary<Key, KeyStates> keyStatesMap) : base(GetKeyboardDevice(keyStatesMap), Substitute.For<PresentationSource>(), 1, realKey)
             {
-                SelectionAdapter = selectionAdapter,
-                Advisor = advisor,
-                TextBox = new TextBoxAutoCompleteTextInput { TextBox = textBox }
-            };
-            textBox.Text = "A :a";
-            textBox.CaretIndex = 4;
-            Assert.Equal(4, textBox.CaretIndex);
-            Assert.Equal(4, autoCompleteBox.TextBox.CaretIndex);
-            Assert.True(autoCompleteBox.IsDropDownOpen);
-
-            selectionAdapter.DoCancel();
-
-            Assert.Equal("A :a", textBox.Text);
-            Assert.False(autoCompleteBox.IsDropDownOpen);
-        }
+                if (isSystemKey)
+                {
+                    MarkSystem();
+                }
+                RoutedEvent = ReflectionExtensions.CreateUninitialized<RoutedEvent>();
+            }
 
-        [STAFact]
-        public void HandlesKeyPressesToSelectAndCancelSelections()
-        {
-            var obs = Observable.Return(new BitmapImage());
+            public void MarkSystem()
+            {
+                ReflectionExtensions.Invoke(this, "MarkSystem");
+            }
 
-            var suggestions = new List<AutoCompleteSuggestion>
+            static KeyboardDevice GetKeyboardDevice(IDictionary<Key, KeyStates> keyStatesMap)
             {
-                new AutoCompleteSuggestion("aaaa", obs, ":", ":"),
-                new AutoCompleteSuggestion("bbbb", obs, ":", ":"),
-                new AutoCompleteSuggestion("ccc", obs, ":", ":")
-            };
-            var result = new AutoCompleteResult(2, new ReadOnlyCollection<AutoCompleteSuggestion>(suggestions));
-            var advisor = Mock.Of<IAutoCompleteAdvisor>(
-                a => a.GetAutoCompletionSuggestions(Args.String, Args.Int32) == Observable.Return(result));
-            var selectionAdapter = new TestSelectorSelectionAdapter();
-            var textBox = new TextBox();
-            var autoCompleteBox = new AutoCompleteBox(Mock.Of<IDpiManager>())
+                return new FakeKeyboardDevice(keyStatesMap);
+            }
+
+            static IDictionary<Key, KeyStates> GetKeyStatesFromPressedKeys(IEnumerable<Key> pressedKeys)
             {
-                SelectionAdapter = selectionAdapter,
-                Advisor = advisor,
-                TextBox = new TextBoxAutoCompleteTextInput { TextBox = textBox }
-            };
-            textBox.Text = "A :a";
-            textBox.CaretIndex = 4;
-            Assert.Equal(4, textBox.CaretIndex);
-            Assert.Equal(4, autoCompleteBox.TextBox.CaretIndex);
-            Assert.True(autoCompleteBox.IsDropDownOpen);
-            selectionAdapter.SelectorControl.SelectedIndex = 1; // Select the second item
-
-            selectionAdapter.DoKeyDown(Key.Enter);
-
-            Assert.Equal("A :bbbb: ", textBox.Text);
-            Assert.False(autoCompleteBox.IsDropDownOpen);
-
-            textBox.Text = "A :bbbb: :";
-            textBox.CaretIndex = 10;
-
-            // Ensure we can re-open the dropdown
-            Assert.True(autoCompleteBox.IsDropDownOpen);
-
-            selectionAdapter.DoKeyDown(Key.Escape);
-            Assert.False(autoCompleteBox.IsDropDownOpen);
-            Assert.Equal("A :bbbb: :", textBox.Text);
+                return pressedKeys == null ? null : pressedKeys.ToDictionary(k => k, k => KeyStates.Down);
+            }
         }
 
-        class TestSelectorSelectionAdapter : SelectorSelectionAdapter
+        public class FakeKeyboardDevice : KeyboardDevice
         {
-            public TestSelectorSelectionAdapter()
-                : base(new ListBox())
-            {
-            }
+            readonly IDictionary<Key, KeyStates> keyStateMap;
 
-            public void DoCommit()
+            public FakeKeyboardDevice(IDictionary<Key, KeyStates> keyStateMap) : base(CreateFakeInputManager())
             {
-                base.OnCommit();
+                this.keyStateMap = keyStateMap ?? new Dictionary<Key, KeyStates>();
             }
 
-            public void DoCancel()
+            protected override KeyStates GetKeyStatesFromSystem(Key key)
             {
-                base.OnCancel();
+                KeyStates keyStates;
+                keyStateMap.TryGetValue(key, out keyStates);
+                return keyStates;
             }
 
-            public void DoKeyDown(Key key)
+            static InputManager CreateFakeInputManager()
             {
-                var keyEventArgs = FakeKeyEventArgs.Create(key, false);
-                HandleKeyDown(keyEventArgs);
+                Castle.DynamicProxy.Generators.AttributesToAvoidReplicating.Add(typeof(System.Security.Permissions.UIPermissionAttribute));
+                // WARNING: This next call is pure evil, but ok here. See the note in the method implementation.
+                return ReflectionExtensions.CreateUninitialized<InputManager>();
             }
         }
+
     }
 }
diff --git a/test/GitHub.UI.UnitTests/Controls/AutoCompleteSuggestionTests.cs b/test/GitHub.UI.UnitTests/Controls/AutoCompleteSuggestionTests.cs
index 66b3d28728..4674997af9 100644
--- a/test/GitHub.UI.UnitTests/Controls/AutoCompleteSuggestionTests.cs
+++ b/test/GitHub.UI.UnitTests/Controls/AutoCompleteSuggestionTests.cs
@@ -1,58 +1,58 @@
 using System.Reactive.Linq;
 using System.Windows.Media.Imaging;
-using GitHub.UI;
+using GitHub.Models;
 using NUnit.Framework;
-using Xunit;
 
-public class AutoCompleteSuggestionTests
+namespace GitHub.UI.UnitTests.Controls
 {
-    public class TheToStringMethod
+    public class AutoCompleteSuggestionTests
     {
-        [Theory]
-        [InlineData(":", ":", ":foo:")]
-        [InlineData("@", "", "@foo")]
-        [InlineData("#", "", "#foo")]
-        [InlineData("@", null, "@foo")]
-        public void ReturnsWordSurroundedByPrefixAndSuffix(string prefix, string suffix, string expected)
+        public class TheToStringMethod
         {
-            var obs = Observable.Return(new BitmapImage());
-            var suggestion = new AutoCompleteSuggestion("foo", obs, prefix, suffix);
-            Assert.Equal(expected, suggestion.ToString());
+            [TestCase(":", ":", ":foo:")]
+            [TestCase("@", "", "@foo")]
+            [TestCase("#", "", "#foo")]
+            [TestCase("@", null, "@foo")]
+            public void ReturnsWordSurroundedByPrefixAndSuffix(string prefix, string suffix, string expected)
+            {
+                var obs = Observable.Return(new BitmapImage());
+                var suggestion = new AutoCompleteSuggestion("foo", obs, prefix, suffix);
+                Assert.AreEqual(expected, suggestion.ToString());
+            }
         }
-    }
 
-    public class TheGetSortRankMethod
-    {
-        [Theory]
-        [InlineData("pat", "full name", 1)]
-        [InlineData("yosemite", "pat name", 0)]
-        [InlineData("minnie", "full pat", 0)]
-        [InlineData("patrick", "full name", 1)]
-        [InlineData("groot", "patrick name", 0)]
-        [InlineData("driver", "danica patrick", 0)]
-        [InlineData("patricka", "pat name", 1)]
-        [InlineData("nomatch", "full name", -1)]
-        public void ReturnsCorrectScoreForSuggestions(string login, string name, int expectedRank)
+        public class TheGetSortRankMethod
         {
-            var obs = Observable.Return(new BitmapImage());
+            [TestCase("pat", "full name", 1)]
+            [TestCase("yosemite", "pat name", 0)]
+            [TestCase("minnie", "full pat", 0)]
+            [TestCase("patrick", "full name", 1)]
+            [TestCase("groot", "patrick name", 0)]
+            [TestCase("driver", "danica patrick", 0)]
+            [TestCase("patricka", "pat name", 1)]
+            [TestCase("nomatch", "full name", -1)]
+            public void ReturnsCorrectScoreForSuggestions(string login, string name, int expectedRank)
+            {
+                var obs = Observable.Return(new BitmapImage());
 
-            var suggestion = new AutoCompleteSuggestion(login, name, obs, "@", "");
+                var suggestion = new AutoCompleteSuggestion(login, name, obs, "@", "");
 
-            int rank = suggestion.GetSortRank("pat");
+                int rank = suggestion.GetSortRank("pat");
 
-            Assert.Equal(expectedRank, rank);
-        }
+                Assert.AreEqual(expectedRank, rank);
+            }
 
-        [Fact]
-        public void ReturnsOneForEmptyString()
-        {
-            var obs = Observable.Return(new BitmapImage());
+            [Test]
+            public void ReturnsOneForEmptyString()
+            {
+                var obs = Observable.Return(new BitmapImage());
 
-            var suggestion = new AutoCompleteSuggestion("joe", "namathe", obs, "@", "");
+                var suggestion = new AutoCompleteSuggestion("joe", "namathe", obs, "@", "");
 
-            int rank = suggestion.GetSortRank("");
+                int rank = suggestion.GetSortRank("");
 
-            Assert.Equal(1, rank);
+                Assert.AreEqual(1, rank);
+            }
         }
     }
 }
diff --git a/test/GitHub.UI.UnitTests/Controls/AutoCompleteTextInputExtensionsTests.cs b/test/GitHub.UI.UnitTests/Controls/AutoCompleteTextInputExtensionsTests.cs
index e53a250818..bb9826a7e9 100644
--- a/test/GitHub.UI.UnitTests/Controls/AutoCompleteTextInputExtensionsTests.cs
+++ b/test/GitHub.UI.UnitTests/Controls/AutoCompleteTextInputExtensionsTests.cs
@@ -1,25 +1,29 @@
-using GitHub.UI;
-using GitHub.UI.Controls.AutoCompleteBox;
-using Moq;
-using Xunit;
+using GitHub.UI.Controls.AutoCompleteBox;
+using NSubstitute;
+using NUnit.Framework;
 
-class AutoCompleteTextInputExtensionsTests
+namespace GitHub.UI.UnitTests.Controls
 {
-    public class TheGetExpandedTextMethod
+    class AutoCompleteTextInputExtensionsTests
     {
-        [Theory]
-        [InlineData(":", 1, 0, ":apple: ")]
-        [InlineData(":a", 2, 0, ":apple: ")]
-        [InlineData(":ap", 3, 0, ":apple: ")]
-        [InlineData(":a", 1, 0, ":apple: a")]
-        [InlineData("Test :", 6, 5, "Test :apple: ")]
-        [InlineData("Test :ap", 8, 5, "Test :apple: ")]
-        [InlineData("Test :apother stuff", 8, 5, "Test :apple: other stuff")]
-        public void ReturnsExpandedText(string text, int caretIndex, int completionOffset, string expected)
+        public class TheGetExpandedTextMethod
         {
-            var textInput = Mock.Of<IAutoCompleteTextInput>(t => t.CaretIndex == caretIndex && t.Text == text);
-            var expandedText = textInput.GetExpandedText(":apple:", completionOffset);
-            Assert.Equal(expected, expandedText);
+            [TestCase(":", 1, 0, ":apple: ")]
+            [TestCase(":a", 2, 0, ":apple: ")]
+            [TestCase(":ap", 3, 0, ":apple: ")]
+            [TestCase(":a", 1, 0, ":apple: a")]
+            [TestCase("Test :", 6, 5, "Test :apple: ")]
+            [TestCase("Test :ap", 8, 5, "Test :apple: ")]
+            [TestCase("Test :apother stuff", 8, 5, "Test :apple: other stuff")]
+            public void ReturnsExpandedText(string text, int caretIndex, int completionOffset, string expected)
+            {
+                var textInput = Substitute.For<IAutoCompleteTextInput>();
+                textInput.CaretIndex.Returns(caretIndex);
+                textInput.Text.Returns(text);
+
+                var expandedText = textInput.GetExpandedText(":apple:", completionOffset);
+                Assert.AreEqual(expected, expandedText);
+            }
         }
     }
 }
diff --git a/test/GitHub.UI.UnitTests/GitHub.UI.UnitTests.csproj b/test/GitHub.UI.UnitTests/GitHub.UI.UnitTests.csproj
index 450a540013..a617e415be 100644
--- a/test/GitHub.UI.UnitTests/GitHub.UI.UnitTests.csproj
+++ b/test/GitHub.UI.UnitTests/GitHub.UI.UnitTests.csproj
@@ -2,15 +2,6 @@
   <PropertyGroup>
     <TargetFramework>net46</TargetFramework>
   </PropertyGroup>
-  <ItemGroup>
-    <Compile Remove="Controls\AutoCompleteBoxTests.cs" />
-    <Compile Remove="Controls\AutoCompleteSuggestionTests.cs" />
-    <Compile Remove="Controls\AutoCompleteTextInputExtensionsTests.cs" />
-    <Compile Remove="Helpers\AutoCompleteAdvisorTests.cs" />
-    <Compile Remove="Helpers\AutoCompleteSourceTests.cs" />
-    <Compile Remove="Helpers\IssuesAutoCompleteSourceTests.cs" />
-    <Compile Remove="Helpers\MentionsAutoCompleteSourceTests.cs" />
-  </ItemGroup>
 
   <ItemGroup>
     <Reference Include="System.Xaml" />
@@ -31,19 +22,6 @@
     <Compile Include="..\Helpers\TestBaseClass.cs" />
     <Compile Include="..\Helpers\Urls.cs" />
   </ItemGroup>
-  
-  <ItemGroup>
-    <None Include="Controls\AutoCompleteBoxTests.cs" />
-    <None Include="Controls\AutoCompleteSuggestionTests.cs" />
-    <None Include="Controls\AutoCompleteTextInputExtensionsTests.cs" />
-  </ItemGroup>
-  
-  <ItemGroup>
-    <None Include="Helpers\AutoCompleteAdvisorTests.cs" />
-    <None Include="Helpers\AutoCompleteSourceTests.cs" />
-    <None Include="Helpers\IssuesAutoCompleteSourceTests.cs" />
-    <None Include="Helpers\MentionsAutoCompleteSourceTests.cs" />
-  </ItemGroup>
 
   <ItemGroup>
     <ProjectReference Include="..\..\src\GitHub.UI\GitHub.UI.csproj" />
diff --git a/test/GitHub.UI.UnitTests/Helpers/AutoCompleteAdvisorTests.cs b/test/GitHub.UI.UnitTests/Helpers/AutoCompleteAdvisorTests.cs
index d0f37c8b3e..a85fec36a0 100644
--- a/test/GitHub.UI.UnitTests/Helpers/AutoCompleteAdvisorTests.cs
+++ b/test/GitHub.UI.UnitTests/Helpers/AutoCompleteAdvisorTests.cs
@@ -3,205 +3,227 @@
 using System.Reactive.Linq;
 using System.Threading.Tasks;
 using System.Windows.Media.Imaging;
-using GitHub.Helpers;
-using GitHub.UI;
-using Moq;
-using Xunit;
+using GitHub.Models;
+using GitHub.Services;
+using NSubstitute;
+using NUnit.Framework;
 
-public class AutoCompleteAdvisorTests
+namespace GitHub.UI.UnitTests.Helpers
 {
-    public class TheParseAutoCompletionTokenMethod
+    public class AutoCompleteAdvisorTests
     {
-        [Theory]
-        [InlineData(":", 1, "", 0)]
-        [InlineData(":po", 3, "po", 0)]
-        [InlineData(":po", 2, "p", 0)]
-        [InlineData(":po or no :po", 2, "p", 0)]
-        [InlineData(":po or no :po yo", 13, "po", 10)]
-        [InlineData("This is :poo", 12, "poo", 8)]
-        [InlineData("This is :poo or is it", 12, "poo", 8)]
-        [InlineData("This is\r\n:poo or is it", 13, "poo", 9)]
-        [InlineData("This is :poo or is it :zap:", 12, "poo", 8)]
-        public void ParsesWordOffsetAndType(
-            string text,
-            int caretPosition,
-            string expectedPrefix,
-            int expectedOffset)
+        public class TheParseAutoCompletionTokenMethod
         {
-            var token = AutoCompleteAdvisor.ParseAutoCompletionToken(text, caretPosition, ":");
+            [TestCase(":", 1, "", 0)]
+            [TestCase(":po", 3, "po", 0)]
+            [TestCase(":po", 2, "p", 0)]
+            [TestCase(":po or no :po", 2, "p", 0)]
+            [TestCase(":po or no :po yo", 13, "po", 10)]
+            [TestCase("This is :poo", 12, "poo", 8)]
+            [TestCase("This is :poo or is it", 12, "poo", 8)]
+            [TestCase("This is\r\n:poo or is it", 13, "poo", 9)]
+            [TestCase("This is :poo or is it :zap:", 12, "poo", 8)]
+            public void ParsesWordOffsetAndType(
+                string text,
+                int caretPosition,
+                string expectedPrefix,
+                int expectedOffset)
+            {
+                var token = AutoCompleteAdvisor.ParseAutoCompletionToken(text, caretPosition, ":");
 
-            Assert.Equal(expectedPrefix, token.SearchSearchPrefix);
-            Assert.Equal(expectedOffset, token.Offset);
-        }
+                Assert.AreEqual(expectedPrefix, token.SearchSearchPrefix);
+                Assert.AreEqual(expectedOffset, token.Offset);
+            }
 
-        [Theory]
-        [InlineData("", 0)]
-        [InlineData("foo bar", 0)]
-        [InlineData("This has no special stuff", 5)]
-        [InlineData("This has a : but caret is after the space after it", 13)]
-        public void ReturnsNullForTextWithoutAnyTriggerCharactersMatchingCaretIndex(string text, int caretPosition)
-        {
-            Assert.Null(AutoCompleteAdvisor.ParseAutoCompletionToken(text, caretPosition, ":"));
+            [TestCase("", 0)]
+            [TestCase("foo bar", 0)]
+            [TestCase("This has no special stuff", 5)]
+            [TestCase("This has a : but caret is after the space after it", 13)]
+            public void ReturnsNullForTextWithoutAnyTriggerCharactersMatchingCaretIndex(string text, int caretPosition)
+            {
+                Assert.Null(AutoCompleteAdvisor.ParseAutoCompletionToken(text, caretPosition, ":"));
+            }
+
+            [TestCase("", 1)]
+            [TestCase("", -1)]
+            [TestCase("foo", 4)]
+            [TestCase("foo", -1)]
+            public void ThrowsExceptionWhenCaretIndexIsOutOfRangeOfText(string text, int caretIndex)
+            {
+                Assert.Throws<ArgumentOutOfRangeException>(
+                    () => AutoCompleteAdvisor.ParseAutoCompletionToken(text, caretIndex, ":"));
+            }
         }
 
-        [Theory]
-        [InlineData("", 1)]
-        [InlineData("", -1)]
-        [InlineData("foo", 4)]
-        [InlineData("foo", -1)]
-        public void ThrowsExceptionWhenCaretIndexIsOutOfRangeOfText(string text, int caretIndex)
+        public class TheGetAutoCompletionSuggestionsMethod
         {
-            Assert.Throws<ArgumentOutOfRangeException>(
-                () => AutoCompleteAdvisor.ParseAutoCompletionToken(text, caretIndex, ":"));
-        }
-    }
+            [Test]
+            public async Task ReturnsResultsWhenOnlyTokenTyped()
+            {
+                var obs = Observable.Return(new BitmapImage());
 
-    public class TheGetAutoCompletionSuggestionsMethod
-    {
-        [Fact]
-        public async Task ReturnsResultsWhenOnlyTokenTyped()
-        {
-            var obs = Observable.Return(new BitmapImage());
+                var suggestions = new List<AutoCompleteSuggestion>
+                {
+                    new AutoCompleteSuggestion("rainbow", obs, ":", ":"),
+                    new AutoCompleteSuggestion("poop", obs, ":", ":"),
+                    new AutoCompleteSuggestion("poop_scoop", obs, ":", ":")
+                }.ToObservable();
 
-            var suggestions = new List<AutoCompleteSuggestion>
-            {
-                new AutoCompleteSuggestion("rainbow", obs, ":", ":"),
-                new AutoCompleteSuggestion("poop", obs, ":", ":"),
-                new AutoCompleteSuggestion("poop_scoop", obs, ":", ":")
-            }.ToObservable();
-            var mentionsSource = Mock.Of<IAutoCompleteSource>(c =>
-                c.GetSuggestions() == Observable.Empty<AutoCompleteSuggestion>() && c.Prefix == "@");
-            var emojiSource = Mock.Of<IAutoCompleteSource>(c =>
-                c.GetSuggestions() == suggestions && c.Prefix == ":");
-            var advisor = new AutoCompleteAdvisor(new[] { mentionsSource, emojiSource });
-
-            var result = await advisor.GetAutoCompletionSuggestions(":", 1);
-
-            Assert.Equal(0, result.Offset);
-            Assert.Equal(3, result.Suggestions.Count);
-            Assert.Equal("poop", result.Suggestions[0].Name);
-            Assert.Equal("poop_scoop", result.Suggestions[1].Name);
-            Assert.Equal("rainbow", result.Suggestions[2].Name);
-        }
+                var mentionsSource = Substitute.For<IAutoCompleteSource>();
+                mentionsSource.GetSuggestions().Returns(Observable.Empty<AutoCompleteSuggestion>());
+                mentionsSource.Prefix.Returns("@");
 
-        [Fact]
-        public async Task ReturnsResultsWithNameMatchingToken()
-        {
-            var obs = Observable.Return(new BitmapImage());
+                var emojiSource = Substitute.For<IAutoCompleteSource>();
+                emojiSource.GetSuggestions().Returns(suggestions);
+                emojiSource.Prefix.Returns(":");
 
-            var suggestions = new List<AutoCompleteSuggestion>
-            {
-                new AutoCompleteSuggestion("rainbow", obs, ":", ":"),
-                new AutoCompleteSuggestion("poop", obs, ":", ":"),
-                new AutoCompleteSuggestion("poop_scoop", obs, ":", ":")
-            }.ToObservable();
-            var mentionsSource = Mock.Of<IAutoCompleteSource>(c =>
-                c.GetSuggestions() == Observable.Empty<AutoCompleteSuggestion>() && c.Prefix == "@");
-            var emojiSource = Mock.Of<IAutoCompleteSource>(c =>
-                c.GetSuggestions() == suggestions && c.Prefix == ":");
-            var advisor = new AutoCompleteAdvisor(new[] { mentionsSource, emojiSource });
-
-            var result = await advisor.GetAutoCompletionSuggestions("this is :poo", 12);
-
-            Assert.Equal(8, result.Offset);
-            Assert.Equal(2, result.Suggestions.Count);
-            Assert.Equal("poop", result.Suggestions[0].Name);
-            Assert.Equal("poop_scoop", result.Suggestions[1].Name);
-        }
+                var advisor = new AutoCompleteAdvisor(new[] { mentionsSource, emojiSource });
 
-        [Fact]
-        public async Task ReturnsResultsWithDescriptionMatchingToken()
-        {
-            var obs = Observable.Return(new BitmapImage());
+                var result = await advisor.GetAutoCompletionSuggestions(":", 1);
+
+                Assert.AreEqual(0, result.Offset);
+                Assert.AreEqual(3, result.Suggestions.Count);
+                Assert.AreEqual("poop", result.Suggestions[0].Name);
+                Assert.AreEqual("poop_scoop", result.Suggestions[1].Name);
+                Assert.AreEqual("rainbow", result.Suggestions[2].Name);
+            }
 
-            var suggestions = new List<AutoCompleteSuggestion>
+            [Test]
+            public async Task ReturnsResultsWithNameMatchingToken()
             {
-                new AutoCompleteSuggestion("rainbow", "John Doe", obs, "@", ""),
-                new AutoCompleteSuggestion("poop", "Alice Bob", obs, "@", ""),
-                new AutoCompleteSuggestion("poop_scoop", obs, "@", ""),
-                new AutoCompleteSuggestion("loop", "Jimmy Alice Cooper", obs, "@", ""),
-            }.ToObservable();
-            var mentionsSource = Mock.Of<IAutoCompleteSource>(c =>
-                c.GetSuggestions() == suggestions && c.Prefix == "@");
-            var emojiSource = Mock.Of<IAutoCompleteSource>(c =>
-                c.GetSuggestions() == Observable.Empty<AutoCompleteSuggestion>() && c.Prefix == ":");
-            var advisor = new AutoCompleteAdvisor(new[] { mentionsSource, emojiSource });
-
-            var result = await advisor.GetAutoCompletionSuggestions("this is @alice", 12);
-
-            Assert.Equal(8, result.Offset);
-            Assert.Equal(2, result.Suggestions.Count);
-            Assert.Equal("loop", result.Suggestions[0].Name);
-            Assert.Equal("poop", result.Suggestions[1].Name);
-        }
+                var obs = Observable.Return(new BitmapImage());
 
-        [Fact]
-        public async Task ReturnsMentionsInCorrectOrder()
-        {
-            var obs = Observable.Return(new BitmapImage());
+                var suggestions = new List<AutoCompleteSuggestion>
+                {
+                    new AutoCompleteSuggestion("rainbow", obs, ":", ":"),
+                    new AutoCompleteSuggestion("poop", obs, ":", ":"),
+                    new AutoCompleteSuggestion("poop_scoop", obs, ":", ":")
+                }.ToObservable();
 
-            var suggestions = new List<AutoCompleteSuggestion>
+                var mentionsSource = Substitute.For<IAutoCompleteSource>();
+                mentionsSource.GetSuggestions().Returns(Observable.Empty<AutoCompleteSuggestion>());
+                mentionsSource.Prefix.Returns("@");
+
+                var emojiSource = Substitute.For<IAutoCompleteSource>();
+                emojiSource.GetSuggestions().Returns(suggestions);
+                emojiSource.Prefix.Returns(":");
+
+                var advisor = new AutoCompleteAdvisor(new[] { mentionsSource, emojiSource });
+
+                var result = await advisor.GetAutoCompletionSuggestions("this is :poo", 12);
+
+                Assert.AreEqual(8, result.Offset);
+                Assert.AreEqual(2, result.Suggestions.Count);
+                Assert.AreEqual("poop", result.Suggestions[0].Name);
+                Assert.AreEqual("poop_scoop", result.Suggestions[1].Name);
+            }
+
+            [Test]
+            public async Task ReturnsResultsWithDescriptionMatchingToken()
             {
-                // We need to have more than 10 matches to ensure we grab the most appropriate top ten
-                new AutoCompleteSuggestion("zztop1", "RainbowBright Doe", obs, "@", ""),
-                new AutoCompleteSuggestion("zztop2", "RainbowBright Doe", obs, "@", ""),
-                new AutoCompleteSuggestion("zztop3", "RainbowBright Doe", obs, "@", ""),
-                new AutoCompleteSuggestion("zztop4", "RainbowBright Doe", obs, "@", ""),
-                new AutoCompleteSuggestion("zztop5", "RainbowBright Doe", obs, "@", ""),
-                new AutoCompleteSuggestion("zztop6", "RainbowBright Doe", obs, "@", ""),
-                new AutoCompleteSuggestion("zztop7", "RainbowBright Doe", obs, "@", ""),
-                new AutoCompleteSuggestion("zztop8", "RainbowBright Doe", obs, "@", ""),
-                new AutoCompleteSuggestion("zztop9", "RainbowBright Doe", obs, "@", ""),
-                new AutoCompleteSuggestion("zztop10", "RainbowBright Doe", obs, "@", ""),
-                new AutoCompleteSuggestion("rainbowbright", "Jimmy Alice Cooper", obs, "@", ""),
-                new AutoCompleteSuggestion("apricot", "Bob Rainbow", obs, "@", ""),
-                new AutoCompleteSuggestion("rainbow", "John Doe", obs, "@", ""),
-                new AutoCompleteSuggestion("poop_scoop", obs, "@", ""),
-                new AutoCompleteSuggestion("zeke", "RainbowBright Doe", obs, "@", ""),
-                new AutoCompleteSuggestion("bill", "RainbowBright Doe", obs, "@", "")
-            }.ToObservable();
-            var mentionsSource = Mock.Of<IAutoCompleteSource>(c =>
-                c.GetSuggestions() == suggestions && c.Prefix == "@");
-            var emojiSource = Mock.Of<IAutoCompleteSource>(c =>
-                c.GetSuggestions() == Observable.Empty<AutoCompleteSuggestion>() && c.Prefix == ":");
-            var advisor = new AutoCompleteAdvisor(new[] { mentionsSource, emojiSource });
-
-            var result = await advisor.GetAutoCompletionSuggestions("this is @rainbow sucka", 16);
-
-            Assert.Equal("rainbow", result.Suggestions[0].Name);
-            Assert.Equal("rainbowbright", result.Suggestions[1].Name); 
-            Assert.Equal("apricot", result.Suggestions[2].Name);
-            Assert.Equal("bill", result.Suggestions[3].Name); // Bill and Zeke have the same name
-            Assert.Equal("zeke", result.Suggestions[4].Name); // but the secondary sort is by login
-        }
+                var obs = Observable.Return(new BitmapImage());
 
-        [Theory]
-        [InlineData("", 0)]
-        [InlineData("Foo bar baz", 0)]
-        [InlineData("Foo bar baz", 3)]
-        public async Task ReturnsEmptyAutoCompleteResult(string text, int caretIndex)
-        {
-            var autoCompleteSource = Mock.Of<IAutoCompleteSource>(
-                c => c.GetSuggestions() == Observable.Empty<AutoCompleteSuggestion>() && c.Prefix == ":");
+                var suggestions = new List<AutoCompleteSuggestion>
+                {
+                    new AutoCompleteSuggestion("rainbow", "John Doe", obs, "@", ""),
+                    new AutoCompleteSuggestion("poop", "Alice Bob", obs, "@", ""),
+                    new AutoCompleteSuggestion("poop_scoop", obs, "@", ""),
+                    new AutoCompleteSuggestion("loop", "Jimmy Alice Cooper", obs, "@", ""),
+                }.ToObservable();
+
+                var mentionsSource = Substitute.For<IAutoCompleteSource>();
+                mentionsSource.GetSuggestions().Returns(suggestions);
+                mentionsSource.Prefix.Returns("@");
+
+                var emojiSource = Substitute.For<IAutoCompleteSource>();
+                emojiSource.GetSuggestions().Returns(Observable.Empty<AutoCompleteSuggestion>());
+                emojiSource.Prefix.Returns(":");
+
+                var advisor = new AutoCompleteAdvisor(new[] { mentionsSource, emojiSource });
 
-            var advisor = new AutoCompleteAdvisor(new[] {autoCompleteSource});
+                var result = await advisor.GetAutoCompletionSuggestions("this is @alice", 12);
+
+                Assert.AreEqual(8, result.Offset);
+                Assert.AreEqual(2, result.Suggestions.Count);
+                Assert.AreEqual("loop", result.Suggestions[0].Name);
+                Assert.AreEqual("poop", result.Suggestions[1].Name);
+            }
+
+            [Test]
+            public async Task ReturnsMentionsInCorrectOrder()
+            {
+                var obs = Observable.Return(new BitmapImage());
+
+                var suggestions = new List<AutoCompleteSuggestion>
+                {
+                    // We need to have more than 10 matches to ensure we grab the most appropriate top ten
+                    new AutoCompleteSuggestion("zztop1", "RainbowBright Doe", obs, "@", ""),
+                    new AutoCompleteSuggestion("zztop2", "RainbowBright Doe", obs, "@", ""),
+                    new AutoCompleteSuggestion("zztop3", "RainbowBright Doe", obs, "@", ""),
+                    new AutoCompleteSuggestion("zztop4", "RainbowBright Doe", obs, "@", ""),
+                    new AutoCompleteSuggestion("zztop5", "RainbowBright Doe", obs, "@", ""),
+                    new AutoCompleteSuggestion("zztop6", "RainbowBright Doe", obs, "@", ""),
+                    new AutoCompleteSuggestion("zztop7", "RainbowBright Doe", obs, "@", ""),
+                    new AutoCompleteSuggestion("zztop8", "RainbowBright Doe", obs, "@", ""),
+                    new AutoCompleteSuggestion("zztop9", "RainbowBright Doe", obs, "@", ""),
+                    new AutoCompleteSuggestion("zztop10", "RainbowBright Doe", obs, "@", ""),
+                    new AutoCompleteSuggestion("rainbowbright", "Jimmy Alice Cooper", obs, "@", ""),
+                    new AutoCompleteSuggestion("apricot", "Bob Rainbow", obs, "@", ""),
+                    new AutoCompleteSuggestion("rainbow", "John Doe", obs, "@", ""),
+                    new AutoCompleteSuggestion("poop_scoop", obs, "@", ""),
+                    new AutoCompleteSuggestion("zeke", "RainbowBright Doe", obs, "@", ""),
+                    new AutoCompleteSuggestion("bill", "RainbowBright Doe", obs, "@", "")
+                }.ToObservable();
+
+                var mentionsSource = Substitute.For<IAutoCompleteSource>();
+                mentionsSource.GetSuggestions().Returns(suggestions);
+                mentionsSource.Prefix.Returns("@");
+
+                var emojiSource = Substitute.For<IAutoCompleteSource>();
+                emojiSource.GetSuggestions().Returns(Observable.Empty<AutoCompleteSuggestion>());
+                emojiSource.Prefix.Returns(":");
+
+                var advisor = new AutoCompleteAdvisor(new[] { mentionsSource, emojiSource });
+
+                var result = await advisor.GetAutoCompletionSuggestions("this is @rainbow sucka", 16);
+
+                Assert.AreEqual("rainbow", result.Suggestions[0].Name);
+                Assert.AreEqual("rainbowbright", result.Suggestions[1].Name); 
+                Assert.AreEqual("apricot", result.Suggestions[2].Name);
+                Assert.AreEqual("bill", result.Suggestions[3].Name); // Bill and Zeke have the same name
+                Assert.AreEqual("zeke", result.Suggestions[4].Name); // but the secondary sort is by login
+            }
+
+            [Theory]
+            [TestCase("", 0)]
+            [TestCase("Foo bar baz", 0)]
+            [TestCase("Foo bar baz", 3)]
+            public async Task ReturnsEmptyAutoCompleteResult(string text, int caretIndex)
+            {
+                var autoCompleteSource = Substitute.For<IAutoCompleteSource>();
+                autoCompleteSource.GetSuggestions().Returns(Observable.Empty<AutoCompleteSuggestion>());
+                autoCompleteSource.Prefix.Returns(":");
+
+                var advisor = new AutoCompleteAdvisor(new[] {autoCompleteSource});
             
-            var result = await advisor.GetAutoCompletionSuggestions(text, 0);
+                var result = await advisor.GetAutoCompletionSuggestions(text, 0);
 
-            Assert.Same(AutoCompleteResult.Empty, result);
-        }
+                Assert.AreSame(AutoCompleteResult.Empty, result);
+            }
 
-        [Fact]
-        public async Task ReturnsEmptyAutoCompleteResultWhenSourceThrowsException()
-        {
-            var autoCompleteSource = Mock.Of<IAutoCompleteSource>(
-                c => c.GetSuggestions() == Observable.Throw<AutoCompleteSuggestion>(new Exception("FAIL!"))
-                    && c.Prefix == "@");
-            var advisor = new AutoCompleteAdvisor(new[] { autoCompleteSource });
+            [Test]
+            public async Task ReturnsEmptyAutoCompleteResultWhenSourceThrowsException()
+            {
+                var autoCompleteSource = Substitute.For<IAutoCompleteSource>();
+                autoCompleteSource.GetSuggestions().Returns(Observable.Throw<AutoCompleteSuggestion>(new Exception("FAIL!")));
+                autoCompleteSource.Prefix.Returns("@");
+
+                var advisor = new AutoCompleteAdvisor(new[] { autoCompleteSource });
 
-            var result = await advisor.GetAutoCompletionSuggestions("@", 1);
+                var result = await advisor.GetAutoCompletionSuggestions("@", 1);
 
-            Assert.Same(AutoCompleteResult.Empty, result);
+                Assert.AreSame(AutoCompleteResult.Empty, result);
+            }
         }
     }
 }
diff --git a/test/GitHub.UI.UnitTests/Helpers/AutoCompleteSourceTests.cs b/test/GitHub.UI.UnitTests/Helpers/AutoCompleteSourceTests.cs
deleted file mode 100644
index f1a518c190..0000000000
--- a/test/GitHub.UI.UnitTests/Helpers/AutoCompleteSourceTests.cs
+++ /dev/null
@@ -1,89 +0,0 @@
-using System;
-using System.Collections.Generic;
-using System.Reactive.Linq;
-using System.Threading.Tasks;
-using System.Windows.Media.Imaging;
-using GitHub;
-using GitHub.Cache;
-using GitHub.Helpers;
-using GitHub.Models;
-using GitHub.UI;
-using GitHub.ViewModels;
-using Moq;
-using Xunit;
-
-/// <summary>
-/// Tests common to <see cref="MentionsAutoCompleteSource" /> and <see cref="IssuesAutoCompleteSource" />.
-/// Run the actual concrete test classes.
-/// </summary>
-public abstract class AutoCompleteSourceTests<TAutoCompleteSource, TCacheInterface>
-    where TAutoCompleteSource : IAutoCompleteSource
-    where TCacheInterface : class, IAutoCompleteSourceCache
-{
-    [Fact]
-    public async Task LocalRepositoryDoesNotSupportAutoComplete()
-    {
-        var container = new TestContainer();
-        var localRepository = Mock.Of<IRepositoryModel>();
-        container.Setup<ISourceListViewModel>(vm => vm.SelectedRepository).Returns(localRepository);
-        var source = container.Get<TAutoCompleteSource>();
-
-        var suggestions = await source.GetSuggestions().ToList();
-
-        Assert.Empty(suggestions);
-    }
-
-    [Fact]
-    public async Task ReturnsEmptyWhenSourceCacheThrows()
-    {
-        var container = new TestContainer();
-        var gitHubRemote = Mock.Of<IRepositoryHost>(x => x.Address == HostAddress.Create("https://github.com/"));
-        var repository = Mock.Of<IRepositoryModel>(x => x.RepositoryHost == gitHubRemote);
-        container.Setup<ISourceListViewModel>(vm => vm.SelectedRepository).Returns(repository);
-        container.Setup<TCacheInterface>(c => c.RetrieveSuggestions(Args.RepositoryModel))
-            .Returns(Observable.Throw<IReadOnlyList<SuggestionItem>>(new Exception("Shit happened!")));
-        var source = container.Get<TAutoCompleteSource>();
-
-        var suggestions = await source.GetSuggestions().ToList();
-
-        Assert.Empty(suggestions);
-    }
-
-    [Fact]
-    public async Task ReturnsResultForGitHubRepository()
-    {
-        var container = new TestContainer();
-        var expectedAvatar = Mock.Of<BitmapSource>();
-        var gitHubRepository = CreateRepository("https://github.com");
-        container.Setup<ISourceListViewModel>(vm => vm.SelectedRepository).Returns(gitHubRepository);
-        container.Setup<IImageCache>(c => c.GetImage(new Uri("https://githubusercontent.com/a/shiftkey.png")))
-            .Returns(Observable.Return(expectedAvatar));
-
-        var suggestions = new[]
-        {
-            new SuggestionItem("shiftkey", "Nice guy", new Uri("https://githubusercontent.com/a/shiftkey.png"))
-        };
-        container.Setup<TCacheInterface>(c  => c.RetrieveSuggestions(gitHubRepository))
-            .Returns(Observable.Return(suggestions));
-        var source = container.Get<TAutoCompleteSource>();
-
-        var retrieved = await source.GetSuggestions().ToList();
-
-        Assert.NotEmpty(retrieved);
-        Assert.Equal("shiftkey", retrieved[0].Name);
-        Assert.Equal("Nice guy", retrieved[0].Description);
-        await AssertAvatar(expectedAvatar, retrieved[0]);
-    }
-
-    protected IRepositoryModel CreateRepository(string hostAddress)
-    {
-        var gitHubRemote = Mock.Of<IRepositoryHost>(x => x.Address == HostAddress.Create(hostAddress));
-        return Mock.Of<IRepositoryModel>(x => x.RepositoryHost == gitHubRemote);
-    }
-
-    protected virtual async Task AssertAvatar(BitmapSource expected, AutoCompleteSuggestion suggestion)
-    {
-        var avatar = await suggestion.Image;
-        Assert.Same(expected, avatar);
-    }
-}
diff --git a/test/GitHub.UI.UnitTests/Helpers/IssuesAutoCompleteSourceTests.cs b/test/GitHub.UI.UnitTests/Helpers/IssuesAutoCompleteSourceTests.cs
deleted file mode 100644
index 821daec048..0000000000
--- a/test/GitHub.UI.UnitTests/Helpers/IssuesAutoCompleteSourceTests.cs
+++ /dev/null
@@ -1,106 +0,0 @@
-using System;
-using System.Linq;
-using System.Reactive.Linq;
-using System.Threading.Tasks;
-using System.Windows.Media.Imaging;
-using GitHub.Cache;
-using GitHub.Helpers;
-using GitHub.Models;
-using GitHub.UI;
-using GitHub.ViewModels;
-using Xunit;
-
-/// <summary>
-/// Tests of the <see cref="IssuesAutoCompleteSource"/>. Test implementations are in
-/// <see cref="AutoCompleteSourceTests{TAutoCompleteSource, TCacheInterface}"/>
-/// </summary>
-/// <remarks>
-/// THIS CLASS SHOULD ONLY CONTAIN TESTS SPECIFIC TO <see cref="IssuesAutoCompleteSource"/> that deviate from the
-/// behavior in common with all <see cref="IAutoCompleteSource"/> implementations.
-/// </remarks>
-public class IssuesAutoCompleteSourceTests : AutoCompleteSourceTests<IssuesAutoCompleteSource, IIssuesCache>
-{
-    [Fact]
-    public async Task ReturnsIssuesSortedByLastModified()
-    {
-        var container = new TestContainer();
-        var gitHubRepository = CreateRepository("https://github.com");
-        container.Setup<ISourceListViewModel>(vm => vm.SelectedRepository).Returns(gitHubRepository);
-
-        var suggestions = new[]
-        {
-            new SuggestionItem("100", "We should do this") { LastModifiedDate = DateTimeOffset.UtcNow.AddDays(-1) },
-            new SuggestionItem("101", "This shit is broken") { LastModifiedDate = DateTimeOffset.UtcNow },
-            new SuggestionItem("102", "What even?")  { LastModifiedDate = DateTimeOffset.UtcNow.AddHours(-1) }
-        };
-        container.Setup<IIssuesCache>(c => c.RetrieveSuggestions(gitHubRepository))
-            .Returns(Observable.Return(suggestions));
-        var source = container.Get<IssuesAutoCompleteSource>();
-
-        var retrieved = await source.GetSuggestions().ToList();
-
-        Assert.NotEmpty(retrieved);
-        retrieved = retrieved.OrderByDescending(r => r.GetSortRank("")).ToList();
-        Assert.Equal("101", retrieved[0].Name);
-        Assert.Equal("102", retrieved[1].Name);
-        Assert.Equal("100", retrieved[2].Name);
-    }
-
-    [Fact]
-    public async Task ReturnsIssuesFilteredByIssueNumber()
-    {
-        var container = new TestContainer();
-        var gitHubRepository = CreateRepository("https://github.com");
-        container.Setup<ISourceListViewModel>(vm => vm.SelectedRepository).Returns(gitHubRepository);
-
-        var suggestions = new[]
-        {
-            new SuggestionItem("#200", "We should do this") { LastModifiedDate = DateTimeOffset.UtcNow.AddDays(-1) },
-            new SuggestionItem("#101", "This shit is broken") { LastModifiedDate = DateTimeOffset.UtcNow },
-            new SuggestionItem("#210", "What even?")  { LastModifiedDate = DateTimeOffset.UtcNow.AddHours(-1) }
-        };
-        container.Setup<IIssuesCache>(c => c.RetrieveSuggestions(gitHubRepository))
-            .Returns(Observable.Return(suggestions));
-        var source = container.Get<IssuesAutoCompleteSource>();
-
-        var retrieved = await source.GetSuggestions().ToList();
-
-        Assert.NotEmpty(retrieved);
-        retrieved = retrieved.OrderByDescending(r => r.GetSortRank("2")).ToList();
-        Assert.Equal("#200", retrieved[0].Name);
-        Assert.Equal("#210", retrieved[1].Name);
-        Assert.Equal("#101", retrieved[2].Name);
-    }
-
-    [Fact]
-    public async Task ReturnsIssuesFilteredByText()
-    {
-        var container = new TestContainer();
-        var gitHubRepository = CreateRepository("https://github.com");
-        container.Setup<ISourceListViewModel>(vm => vm.SelectedRepository).Returns(gitHubRepository);
-
-        var suggestions = new[]
-        {
-            new SuggestionItem("#200", "We should do this") { LastModifiedDate = DateTimeOffset.UtcNow.AddDays(-1) },
-            new SuggestionItem("#101", "This shit is broken") { LastModifiedDate = DateTimeOffset.UtcNow },
-            new SuggestionItem("#210", "What even?")  { LastModifiedDate = DateTimeOffset.UtcNow.AddHours(-1) }
-        };
-        container.Setup<IIssuesCache>(c => c.RetrieveSuggestions(gitHubRepository))
-            .Returns(Observable.Return(suggestions));
-        var source = container.Get<IssuesAutoCompleteSource>();
-
-        var retrieved = await source.GetSuggestions().ToList();
-
-        Assert.NotEmpty(retrieved);
-        retrieved = retrieved.OrderByDescending(r => r.GetSortRank("shit")).ToList();
-        Assert.Equal("#101", retrieved[0].Name); 
-        Assert.Equal("#200", retrieved[1].Name);
-        Assert.Equal("#210", retrieved[2].Name);
-    }
-
-    protected override Task AssertAvatar(BitmapSource expected, AutoCompleteSuggestion suggestion)
-    {
-        // Issues do not have images associated with them so we'll just ignore the avatar when asserting it.
-        return Task.FromResult(0);
-    }
-}
diff --git a/test/GitHub.UI.UnitTests/Helpers/MentionsAutoCompleteSourceTests.cs b/test/GitHub.UI.UnitTests/Helpers/MentionsAutoCompleteSourceTests.cs
deleted file mode 100644
index 399f05c2b7..0000000000
--- a/test/GitHub.UI.UnitTests/Helpers/MentionsAutoCompleteSourceTests.cs
+++ /dev/null
@@ -1,13 +0,0 @@
-using GitHub.Helpers;
-
-/// <summary>
-/// Tests of the <see cref="MentionsAutoCompleteSource"/>. Test implementations are in
-/// <see cref="AutoCompleteSourceTests{TAutoCompleteSource, TCacheInterface}"/>
-/// </summary>
-/// <remarks>
-/// THIS CLASS SHOULD ONLY CONTAIN TESTS SPECIFIC TO <see cref="MentionsAutoCompleteSource"/> that deviate from the
-/// behavior in common with all <see cref="IAutoCompleteSource"/> implementations.
-/// </remarks>
-public class MentionsAutoCompleteSourceTests : AutoCompleteSourceTests<MentionsAutoCompleteSource, IMentionsCache>
-{
-}