Define certain areas on the stage as the stage?

programming flash
1

Is it possible to define only certain areas of the stage as the actual stage? As to say if I have the following code:

stage.addEventListener(MouseEvent.CLICK, burnIt);
function burnIt(event:MouseEvent):void {
timer.start();
timer2.start();
}

Is it possible to define only a section of the stage as clickable? Maybe within a mask? Also from the code above, how do a stop the timer with another click?

Thanks