Bug 65762 [Viewers] Need to back out of change to AbstractTreeViewer.isExpandable
bundles/org.eclipse.jface/src/org/eclipse/jface/viewers/AbstractTreeViewer.java
* Removes a listener for expand and collapse events in this viewer. Has no
	 * affect if an identical listener is not registered.
	 * 
	 * @param listener
	 *           a tree viewer listener
	 */
	public void removeTreeListener(ITreeViewerListener listener) {
		treeListeners.remove(listener);
	}
	
	public void reveal(Object element) {
		Assert.isNotNull(element);
		Widget w = internalExpand(element, true);
		if (w instanceof Item)
			showItem((Item) w);
	}
	/**
	 * Returns the rightmost visible descendent of the given item. Returns the
	 * item itself if it has no children.
	 * 
	 * @param item
	 *           the item to compute the descendent of
	 * @return the rightmost visible descendent or the item iself if it has no
	 *         children
	 */
	private Item rightMostVisibleDescendent(Item item) {
		Item[] children = getItems(item);
		if (getExpanded(item) && children != null && children.length > 0) {
			return rightMostVisibleDescendent(children[children.length - 1]);
		}