private var spantop:Spacer=new Spacer();
           private function heigthiws():void
           {
            //spantop.height=0;
        this.addChild(spantop);
             var heirts:int=Math.round(stage.stageHeight/3.386);
        if(heirts>1){
        spantop.height=heirts;//不起做用,为什么呢?
        Alert.show(heirts.toString());//这里又可以显示出数来,请达人帮助.
              }
      }