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
if (element == null) {
			internalRefresh(getControl(), getRoot(), true, updateLabels);
			return;
		}
		Widget[] items = findItems(element);
		if (items.length != 0) {
			for (int i = 0; i < items.length; i++) {
				
				internalRefresh(items[i], element, true, updateLabels);
			}
		}
	}
	/**
	 * Refreshes the tree starting at the given widget.
	 * <p>
	 * EXPERIMENTAL. Not to be used except by JDT. This method was added to
	 * support JDT's explorations into grouping by working sets, which requires
	 * viewers to support multiple equal elements. See bug 76482 for more
	 * 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
	 * @param element
	 *            the element
	 * @param doStruct
	 *            <code>true</code> if structural changes are to be picked up,
	 *            and <code>false</code> if only label provider changes are of