Bug 172019 [Viewers] Plus sign doesn't disappear when using deferred content providers
3.3 M4 Use a tree viewer with a content provider using IDeferredWorkbenchAdapter and DeferredTreeContentManager. When fetchDeferredChildren is call and no elements are reported to the element collector the plus sign of the node doesn't disappear. This work without problems under Windows and Mac/OS (e.g. the plus sign disappears).
bundles/org.eclipse.jface/src/org/eclipse/jface/viewers/AbstractTreeViewer.java
* 
	 * @param listener
	 *            a tree viewer listener
	 */
	public void removeTreeListener(ITreeViewerListener listener) {
		treeListeners.remove(listener);
	}
	/**
	 * This implementation of reveal() reveals the given element or tree path.
	 */
	public void reveal(Object elementOrTreePath) {
		Assert.isNotNull(elementOrTreePath);
		Widget w = internalExpand(elementOrTreePath, 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]);