In the following example I will demonstrate how to use addEventListener to add a click event to a button that is built using the new SimpleButton object. The SimpleButton is a light weight alternative to the heavier MovieClip object.

package ca.flashdev.example {		

  import flash.display.Sprite;
  import flash.display.Shape;
  import flash.display.SimpleButton;
  import flash.events.MouseEvent;
  import flash.events.Event;

  public class ButtonTrace extends Sprite {		

    private var __button:SimpleButton = new SimpleButton();

    public function ButtonTrace():void {
      drawButton();
      activateButton();
    }

    private function drawButton():void {

      var down:Sprite = new Sprite();
      down.graphics.lineStyle(1, 0x000000);
      down.graphics.beginFill(0xFFCC00);
      down.graphics.drawRect(10, 10, 100, 30);

      var up:Sprite = new Sprite();
      up.graphics.lineStyle(1, 0x000000);
      up.graphics.beginFill(0x0099FF);
      up.graphics.drawRect(10, 10, 100, 30);

      var over:Sprite = new Sprite();
      over.graphics.lineStyle(1, 0x000000);
      over.graphics.beginFill(0x9966FF);
      over.graphics.drawRect(10, 10, 100, 30);

      __button.upState = up;
      __button.overState = over;
      __button.downState = down;
      __button.useHandCursor = true;
      __button.hitTestState = up;

      addChild(__button);
    }

    private function activateButton():void {
      __button.addEventListener(MouseEvent.CLICK, displayMessage);
    }

    private function displayMessage(e:Event):void {
      trace("Don't push my buttons!");
    }
  }
}

Save this file as ButtonTrace.as in a folder structure of ca.flashdev.example.
Create a new movie and add ca.flashdev.example.ButtonTrace to the ActionScript 3.0 Settings Document class field. Save this file as button.fla in the same directory as your ca folder. Publish (Ctrl+Enter) your movie and you should see a button that you can click.

Download the source files