tree节点自动展开

网上找过很多，都好像效果不明显，
下面是自己改进的一个，flex3测试可行：

setTimeout(treeExpand, 1000); //延时1秒

private function treeExpand():void
{ 
	tree.selectedIndex=1;
	openItem(tree,District(tree.selectedItem));
}
		
private function openItem(tree:NodeTree, treeItem:District):void
{
	tree.expandItem(treeItem,true);
	if(treeItem.children && treeItem.children.length>0){
		for(var i:int=0;i<treeItem.children.length;i++){
			var item:District = treeItem.children.getItemAt(i) as District;
				(treeItem){
					openItem(tree, item);
				}
			}
		}
	}
}