//全部展開，初始選中第一項

treePlayList.dataProvider=results;//刷新Tree的全部節點展開 - royanxin - royanxin的博客

treePlayList.validateNow(); //驗證并更新此對象的屬性和布局，并重繪該對象（如果需要）。

treePlayList.selectedIndex=0;

treePlayList.expandChildrenOf(treePlayList.selectedItem,true);//全部展開

setTimeout(IniExpand, 1000); //延時1秒

private function IniExpand():void {
TreeView1.selectedIndex=1;
TreeView1.expandItem(TreeView1.selectedItem,true);
}

//全部展開，初始未選中任何選項
sysTree.validateNow();
for each(var item:XML in this.sysTree.dataProvider){
sysTree.expandChildrenOf(item,true);
}