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
*            the tree item for the element
	 * @param parentPath
	 *            the parent path if it is knwon or <code>null</code> if it
	 *            needs to be determines
	 * @param element
	 *            the element
	 * @return whether the given element is expandable
	 */
	private boolean isExpandable(Item item, TreePath parentPath, Object element) {
		Object elementOrTreePath = element;
		if (isTreePathContentProvider()) {
			if (parentPath != null) {
				elementOrTreePath = parentPath.createChildPath(element);
			} else {
				elementOrTreePath = getTreePathFromItem(item);
			}
		}
		return isExpandable(elementOrTreePath);
	}
	
	protected void labelProviderChanged() {
		
		Control tree = getControl();
		tree.setRedraw(false);
		
		internalRefresh(tree, getRoot(), false, true);
		tree.setRedraw(true);
	}
	/**
	 * Creates a new item.