race_btn.addEventListener(MouseEvent.CLICK, race); var tmr:Timer = new Timer(200); tmr.addEventListener("timer", raceEm); function race(evt:MouseEvent):void { tmr.start(); } function raceEm(evt:Event):void { r1.x += Math.random()*12; r2.x += Math.random()*12; r3.x += Math.random()*12; r4.x += Math.random()*12; if (r1.x > finish.x || r2.x > finish.x || r3.x > finish.x || r4.x > finish.x) { tmr.stop(); } }