Bug 153993 [Viewers] Common Baseclass for Tree/TableEditorImpl
bundles/org.eclipse.jface/src/org/eclipse/jface/viewers/TreeViewer.java
Object element = item.getData();
			itemSet.put(element, element);
		}
		
		
		for (int i = 0; i < current.length; i++) {
			if (current[i].getData() == null
					|| !itemSet.containsKey(current[i].getData())) {
				return false;
			}
		}
		return true;
	}
	/*
	 * (non-Javadoc) Method declared in AbstractTreeViewer.
	 */
	protected void showItem(Item item) {
		getTree().showItem((TreeItem) item);
	}
	/*
	 * (non-Javadoc)
	 * 
	 * @see org.eclipse.jface.viewers.AbstractTreeViewer#getChild(org.eclipse.swt.widgets.Widget,
	 *      int)
	 */
	protected Item getChild(Widget widget, int index) {
		if (widget instanceof TreeItem) {
			return ((TreeItem) widget).getItem(index);
		}
		if (widget instanceof Tree) {