Bug 89137 [JFace] - API Review - "temporary" API in AbstractTreeViewer
AbstractTreeViewer contains two methods documented as "temporary" internalRefresh(Widget, Object) internalAdd(Widget, Object, Object [])
bundles/org.eclipse.jface/src/org/eclipse/jface/viewers/StructuredViewer.java
*/
	protected void handleOpen(SelectionEvent event) {
		Control control = getControl();
		if (control != null && !control.isDisposed()) {
			ISelection selection = getSelection();
			fireOpen(new OpenEvent(this, selection));
		}
	}
	/**
	 * Handles an invalid selection.
	 * <p>
	 * This framework method is called if a model change picked up by a viewer
	 * results in an invalid selection. For instance if an element contained in
	 * the selection has been removed from the viewer, the viewer is free to
	 * either remove the element from the selection or to pick another element
	 * as its new selection. The default implementation of this method calls
	 * <code>updateSelection</code>. Subclasses may override it to implement
	 * a different strategy for picking a new selection when the old selection
	 * becomes invalid.
	 * </p>
	 * 
	 * @param invalidSelection
	 *            the selection before the viewer was updated
	 * @param newSelection
	 *            the selection after the update, or <code>null</code> if none
	 */
	protected void handleInvalidSelection(ISelection invalidSelection, ISelection newSelection) {
		updateSelection(newSelection);
		SelectionChangedEvent event = new SelectionChangedEvent(this, newSelection);
		firePostSelectionChanged(event);