Abstract Text Editor: don't change StyledText by CSS.

Fix for #869

bundles/org.eclipse.ui.workbench.texteditor/src/org/eclipse/ui/texteditor/AbstractTextEditor.java

@@ -2276,11 +2276,6 @@ private int computeOffsetAtLocation(ITextViewer textViewer, int x, int y) {
 	/** The width of the vertical ruler. */
 	protected static final int VERTICAL_RULER_WIDTH= 12;
 
-	/*
-	 * The colors of AbstractTextEditor can be configured by the "Text Editors"
-	 * preferences. This color configuration will be changed by theming. This means
-	 * no need for CSS basecolors here.
-	 */
 	private static final String DISABLE_CSS = "org.eclipse.e4.ui.css.disabled"; //$NON-NLS-1$
 
 	/**
@@ -3373,6 +3368,9 @@ public void createPartControl(Composite parent) {
 		int styles= SWT.V_SCROLL | SWT.H_SCROLL | SWT.MULTI | SWT.BORDER | SWT.FULL_SELECTION;
 		fSourceViewer= createSourceViewer(parent, fVerticalRuler, styles);
 
+		// We're managing our appearance from our preferences. Disable CSS styling.
+		// The CSS engine does set the editor preferences on theme switches, so we
+		// will pick up changes.
 		fSourceViewer.getTextWidget().setData(DISABLE_CSS, Boolean.TRUE);
 
 		if (fConfiguration == null)