Actionscript 3.0 - Timer

var myTimer:Timer = new Timer(40);
myTimer.addEventListener(TimerEvent.TIMER, moveBall);
myTimer.start();

function moveBall(event:Event):void
{
if (ball_mc.x < stage.stageWidth - ball_mc.width && ball_mc.y < stage.stageHeight - ball_mc.height)
{
ball_mc.x += 5;
ball_mc.y += 1;
}
else
{
myTimer.stop();
}
}