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
setDescription(JavaUIMessages.getString("JavaEditorPreferencePage.description")); 
		setPreferenceStore(JavaPlugin.getDefault().getPreferenceStore());
		fOverlayStore= new OverlayPreferenceStore(getPreferenceStore(), fKeys);
	}
	
	public static void initDefaults(IPreferenceStore store) {
		
		/* 
		 * Ensure that the display is accessed only in the UI thread.
		 * Ensure that there are no side effects of switching the thread.
		 */
		final RGB[] rgbs= new RGB[3];
		final Display display= Display.getDefault();
		display.syncExec(new Runnable() {
			public void run() {
				Color c= display.getSystemColor(SWT.COLOR_GRAY);
				rgbs[0]= c.getRGB();
				c= display.getSystemColor(SWT.COLOR_LIST_FOREGROUND);
				rgbs[1]= c.getRGB();
				c= display.getSystemColor(SWT.COLOR_LIST_BACKGROUND);
				rgbs[2]= c.getRGB();
			}
		});
		
		
		/* 
		 * Go on in whatever thread this is. 
		 */
		store.setDefault(CompilationUnitEditor.MATCHING_BRACKETS, true);
		PreferenceConverter.setDefault(store, CompilationUnitEditor.MATCHING_BRACKETS_COLOR,  rgbs[0]);