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
* Returns all selected items for the given SWT control.
	 * 
	 * @param control
	 *            the control
	 * @return the list of selected items
	 */
	protected abstract Item[] getSelection(Control control);
	/*
	 * (non-Javadoc)
	 * 
	 * @see org.eclipse.jface.viewers.StructuredViewer#getSelectionFromWidget()
	 */
	protected List getSelectionFromWidget() {
		Widget[] items = getSelection(getControl());
		ArrayList list = new ArrayList(items.length);
		for (int i = 0; i < items.length; i++) {
			Widget item = items[i];
			Object e = item.getData();
			if (e != null) {
				list.add(e);
			}
		}
		return list;
	}
	/*
	 * Overridden in AbstractTreeViewer to fix bug 108102 (code copied from
	 * StructuredViewer to avoid introducing new API) (non-Javadoc)
	 * 
	 * @see org.eclipse.jface.viewers.StructuredViewer#handleDoubleSelect(org.eclipse.swt.events.SelectionEvent)
	 */