Display scroll bar of admin store switcher in OSX computers. When not displayed people do not notice that the menu is scrollable and you think there is an issue with the stores that are not displayed

Author: jalogut

app/design/adminhtml/Magento/backend/Magento_Backend/web/css/source/module/main/actions-bar/_store-switcher.less

@@ -42,6 +42,14 @@
         max-height: 250px;
         overflow-y: auto;
         padding-top: .25em;
+        &::-webkit-scrollbar {
+            -webkit-appearance: none;
+            width: 7px;
+        }
+        &::-webkit-scrollbar-thumb {
+            border-radius: 4px;
+            background-color: rgba(0, 0, 0, .5);
+        }
 
         li {
             border: 0;