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
* details. This support will likely be removed in Eclipse 3.2 in favour of
	 * proper support for multiple equal elements.
	 * </p>
	 * 
	 * @param widget
	 *            the widget for the parent element
	 * @param parentElementOrTreePath
	 *            the parent element
	 * @param childElements
	 *            the child elements to add
	 * @since 3.1
	 */
	protected void internalAdd(Widget widget, Object parentElementOrTreePath,
			Object[] childElements) {
		Object parent;
		TreePath path;
		if (parentElementOrTreePath instanceof TreePath) {
			path = (TreePath) parentElementOrTreePath;
			parent = path.getLastSegment();
		} else {
			parent = parentElementOrTreePath;
			path = null;
		}
		
		
		if (widget instanceof Item) {
			Item ti = (Item) widget;
			if (!getExpanded(ti)) {
				boolean needDummy = isExpandable(ti, path, parent);
				boolean haveDummy = false;