Bug 305703 [Viewers][CommonNavigator] remembered contributions can leak when using filters
bundles/org.eclipse.jface/src/org/eclipse/jface/viewers/StructuredViewer.java
*            <code>false</code> to only update labels as needed, assuming
	 *            that labels for existing elements are unchanged.
	 * 
	 * @since 2.0
	 */
	protected void internalRefresh(Object element, boolean updateLabels) {
		internalRefresh(element);
	}
	/**
	 * Adds the element item pair to the element map.
	 * <p>
	 * This method is internal to the framework; subclassers should not call
	 * this method.
	 * </p>
	 * 
	 * @param element
	 *            the element
	 * @param item
	 *            the corresponding widget
	 */
	protected void mapElement(Object element, Widget item) {
		if (elementMap != null) {
			Object widgetOrWidgets = elementMap.get(element);
			if (widgetOrWidgets == null) {
				elementMap.put(element, item);
			} else if (widgetOrWidgets instanceof Widget) {
				if (widgetOrWidgets != item) {
					elementMap.put(element, new Widget[] {
							(Widget) widgetOrWidgets, item });
				}