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 (widget == tree && oldCnt == 0 && getItemCount(tree) != 0) {
			
			tree.setRedraw(false);
			tree.setRedraw(true);
		}
	}
	/**
	 * Updates the "+"/"-" icon of the tree node from the given element. It
	 * calls <code>isExpandable</code> to determine whether an element is
	 * expandable.
	 * 
	 * @param item
	 *            the item
	 * @param element
	 *            the element
	 */
	protected void updatePlus(Item item, Object element) {
		boolean hasPlus = getItemCount(item) > 0;
		boolean needsPlus = isExpandable(item, null, element);
		boolean removeAll = false;
		boolean addDummy = false;
		Object data = item.getData();
		if (data != null && equals(element, data)) {
			
			if (hasPlus != needsPlus) {
				if (needsPlus) {
					addDummy = true;
				} else {
					removeAll = true;
				}