private function init():void
    {
     sprite = new Sprite();
     sprite.graphics.lineStyle(2);
     sprite.graphics.beginFill(0xffff00);
     sprite.graphics.drawRect(-50, -50, 100, 100);
     sprite.graphics.endFill();
     sprite.x = 200;
     sprite.y = 200;
     addChild(sprite);
     
     filter = new DropShadowFilter(0, 0, 0, 1, 20, 20, .3);
     
     addEventListener(Event.ENTER_FRAME, onEnterFrame);
    }