Remember theme across tabs within the same session

Reported by @acardona, #56 (comment)

Author: tferr

src/main/java/org/scijava/ui/swing/script/EditorPane.java

@@ -63,6 +63,7 @@
 import org.fife.ui.rsyntaxtextarea.RSyntaxTextArea;
 import org.fife.ui.rsyntaxtextarea.Style;
 import org.fife.ui.rsyntaxtextarea.SyntaxScheme;
+import org.fife.ui.rsyntaxtextarea.Theme;
 import org.fife.ui.rtextarea.Gutter;
 import org.fife.ui.rtextarea.GutterIconInfo;
 import org.fife.ui.rtextarea.RTextArea;
@@ -837,8 +838,7 @@ public void convertSpacesToTabs() {
 	public static final String DEFAULT_THEME = "default";
 
 	/**
-	 * Loads and applies the preferences for the tab (theme excluded).
-	 * @see TextEditor#applyTheme(String)
+	 * Loads and applies the preferences for the tab
 	 */
 	public void loadPreferences() {
 		if (prefService == null) {
@@ -862,13 +862,47 @@ public void loadPreferences() {
 			setKeylessAutoCompletion(prefService.getBoolean(getClass(), AUTOCOMPLETE_KEYLESS_PREFS, true)); // true for backwards compatibility with IJ1 macro
 			setFallbackAutoCompletion(prefService.getBoolean(getClass(), AUTOCOMPLETE_FALLBACK_PREFS, false));
 			setMarkOccurrences(prefService.getBoolean(getClass(), MARK_OCCURRENCES_PREFS, false));
+			applyTheme(themeName());
+		}
+	}
+
+	/**
+	 * Applies a theme to this pane.
+	 *
+	 * @param theme either "default", "dark", "druid", "eclipse", "idea", "monokai",
+	 *              "vs"
+	 * @throws IllegalArgumentException If {@code theme} is not a valid option, or
+	 *                                  the resource could not be loaded
+	 */
+	public void applyTheme(final String theme) throws IllegalArgumentException {
+		try {
+			applyTheme(getTheme(theme));
+		} catch (final Exception ex) {
+			throw new IllegalArgumentException(ex);
 		}
 	}
 
 	public String themeName() {
 		return prefService.get(getClass(), THEME_PREFS, DEFAULT_THEME);
 	}
 
+	private void applyTheme(final Theme th) throws IllegalArgumentException {
+		// themes include font size, so we'll need to reset that
+		final float existingFontSize = getFontSize();
+		th.apply(this);
+		setFontSize(existingFontSize);
+		updateBookmarkIcon(); // update bookmark icon color
+	}
+
+	private static Theme getTheme(final String theme) throws IllegalArgumentException {
+		try {
+			return Theme
+					.load(TextEditor.class.getResourceAsStream("/org/fife/ui/rsyntaxtextarea/themes/" + theme + ".xml"));
+		} catch (final Exception ex) {
+			throw new IllegalArgumentException(ex);
+		}
+	}
+
 	public String loadFolders() {
 		return prefService.get(getClass(), FOLDERS_PREFS, System.getProperty("user.home"));
 	}

src/main/java/org/scijava/ui/swing/script/TextEditor.java

@@ -132,7 +132,6 @@
 
 import org.fife.ui.rsyntaxtextarea.AbstractTokenMakerFactory;
 import org.fife.ui.rsyntaxtextarea.RSyntaxTextArea;
-import org.fife.ui.rsyntaxtextarea.Theme;
 import org.fife.ui.rsyntaxtextarea.TokenMakerFactory;
 import org.scijava.Context;
 import org.scijava.app.AppService;
@@ -1494,9 +1493,11 @@ private JMenu applyThemeMenu() {
 			item.addActionListener(e -> {
 				try {
 					applyTheme(v, false);
+					// make the choice available for the next tab
+					prefService.put(EditorPane.class, EditorPane.THEME_PREFS, v);
 				} catch (final IllegalArgumentException ex) {
 					JOptionPane.showMessageDialog(TextEditor.this,
-							"An exception occured. Theme could not be loaded");
+							"An exception occured. Theme could not be loaded.");
 					ex.printStackTrace();
 				}
 			});
@@ -1519,21 +1520,22 @@ public void applyTheme(final String theme) throws IllegalArgumentException {
 
 	private void applyTheme(final String theme, final boolean updateUI) throws IllegalArgumentException {
 		try {
-			final Theme th = Theme
-					.load(getClass().getResourceAsStream("/org/fife/ui/rsyntaxtextarea/themes/" + theme + ".xml"));
 			for (int i = 0; i < tabbed.getTabCount(); i++) {
-				// themes include font size, so we'll need to reset that
-				final EditorPane ep = getEditorPane(i);
-				final float existingFontSize = ep.getFontSize();
-				th.apply(ep);
-				ep.setFontSize(existingFontSize);
-				ep.updateBookmarkIcon(); // update bookmark icon color
+				getEditorPane(i).applyTheme(theme);
 			}
 		} catch (final Exception ex) {
+			activeTheme = "default";
+			updateThemeControls("default");
+			writeError("Could not load theme. See Console for details.");
+			updateThemeControls(activeTheme);
 			throw new IllegalArgumentException(ex);
 		}
-		this.activeTheme = theme;
-		if (updateUI && themeRadioGroup != null) {
+		activeTheme = theme;
+		if (updateUI) updateThemeControls(theme);
+	}
+
+	private void updateThemeControls(final String theme) {
+		if (themeRadioGroup != null) {
 			final Enumeration<AbstractButton> choices = themeRadioGroup.getElements();
 			while (choices.hasMoreElements()) {
 				final AbstractButton choice = choices.nextElement();