bug？

/**
 * Copyright narutohyper ( http://wonderfl.net/user/narutohyper )
 * MIT License ( http://www.opensource.org/licenses/mit-license.php )
 * Downloaded from: http://wonderfl.net/c/5dF3
 */

package
{
    import flash.display.Sprite;
    import flash.events.Event;
    import flash.display.StageQuality;
    /**
     * ...
     * @author narutohyper
     */
    public class Main extends Sprite
    {
        
        public function Main():void
        {
            if (stage) init();
            else addEventListener(Event.ADDED_TO_STAGE, init);
        }
        
        private function init(e:Event = null):void
        {
            removeEventListener(Event.ADDED_TO_STAGE, init);
            // entry point
            stage.quality = StageQuality.HIGH;
            //LOWだと崩れない・・・
            //stage.quality = StageQuality.LOW;
            this.graphics.lineStyle(50, 0x0, 1,true, "normal");
            this.graphics.beginFill(0xFF0000);
            this.graphics.drawRoundRect(100, 100, 200, 200, 1, 1);
            this.graphics.endFill();
            
            
        }
        
    }
    
}