How to use a listen function from a movieclip

[5TonsOfFlax]

If you don't know coding, how can you be sure that you can't do it with event listeners? And if you're sure you can't do it with event listeners, why did you title this thread "How to use a listen function from a movieclip"?

Here's an outline for how to do it. This is psuedocode and I have left some stuff undefined.

var buttons:Array = [mc1, mc2, mc3];
var current:MovieClip = null;

for (var i:int = 0; i < buttons.length; i++){
  buttons[i].addEventListener(MouseEvent.MOUSE_DOWN, buttonPress);
}

function buttonPress(e:MouseEvent):void{
  if (current != null){
     //code to lighten current.
     current.alpha = 0.3; //replace this with whatever you want to "undo" the press effect
  }
  current = MovieClip(e.currentTarget);
  current.alpha = 1; //again, replace with whatever effect you want on press.
}

I have nothing to open fla files with so I cannot help you with your other problem unless you actually explain it.