Bug 16923 Auto activation preference dialog
The auto activation characters and Timeout Text fields are enabled even when Auto activation itself is disabled. This was confusing to me because I thought that "." should cause automatic code assist, but it wasn't. Disabling the feature should disable the controls what modify the details for that feature.
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/preferences/JavaEditorPreferencePage.java
fPreviewViewer.setDocument(document);
		
		fOverlayStore.addPropertyChangeListener(new IPropertyChangeListener() {
			public void propertyChange(PropertyChangeEvent event) {
				String p= event.getProperty();
				if (p.equals(AbstractTextEditor.PREFERENCE_COLOR_BACKGROUND) ||
					p.equals(AbstractTextEditor.PREFERENCE_COLOR_BACKGROUND_SYSTEM_DEFAULT))
				{
					initializeViewerColors(fPreviewViewer);
				}
				
				fPreviewViewer.invalidateTextPresentation();
			}
		});
		
		return fPreviewViewer.getControl();
	}
	
	/**
	 * Initializes the given viewer's colors.
	 * 
	 * @param viewer the viewer to be initialized
	 */
	private void initializeViewerColors(ISourceViewer viewer) {
		
		IPreferenceStore store= fOverlayStore;
		if (store != null) {
			
			StyledText styledText= viewer.getTextWidget();