private function onMouseDown(event:MouseEvent):void
     {
       drawing = true;
       hold = null;
       beginX = event.localX; beginY = event.localY;
       if (mode == 0) {
        item = new Sprite();
        var c:UIComponent = new UIComponent();
        c.addChild(item);
        item.graphics.lineStyle(3, 0xFF0000);
        item.graphics.moveTo(event.localX, event.localY);
        video.addChild(c);
       }
     }