Flex 确定弹出窗口的绝对位置x , y

var selectbox:Selectbox;

selectbox = new SelectBox();

var pt:Point = new Point(0,0);

pt = this.parent.localToGlobal(pt);

selectbox.y = pt.y + this.Height-3;

selectbox.x = pt.x + this.x;

PopUpManager.addPopUp(selectbox,this,false);