Bug 275910 [Widgets] PaintListener on Tree not invoked when item count is 0
bundles/org.eclipse.ui.ide/src/org/eclipse/ui/internal/views/markers/ExtendedMarkersView.java
/**
	 * @return the viewer
	 */
	TreeViewer getViewer() {
		return viewer;
	}
	/**
	 * The method should not be called directly, see
	 * {@link MarkerUpdateScheduler}
	 * 
	 * Cancel a scheduled delay
	 */
	void cancelQueuedUpdates() {
		synchronized (builder.getUpdateScheduler().getSchedulingLock()) {
			if (uiUpdateJob != null) {
				uiUpdateJob.cancel();
			}
		}
	}
	/**
	 * The method should not be called directly, see
	 * {@link MarkerUpdateScheduler}
	 * 
	 * @param delay
	 * @return UIUpdateJob