private function onEnterFrame(event:Event):void
    {
     angle += .05;
     var cos:Number = Math.cos(angle);
     var sin:Number = Math.sin(angle);
     box.transform.matrix = new Matrix(cos, sin,
              -sin, cos,
               stage.stageWidth / 2,
               stage.stageHeight / 2);
    }
   }
  }