Flex Tree control 點擊branch後展開

Tree control default 是點擊最左邊的三角形才會展開branch

若要在branch click後展開，參考code如下：

在tree 的itemClick event property做一個handlder function

protected function userTree_itemClickHandler(event:ListEvent):void
   {
    var item:Object = Tree(event.currentTarget).selectedItem;
                if (userTree.dataDescriptor.isBranch(item)) {
     userTree.expandItem(item, !userTree.isItemOpen(item), true);
    }
   }