package {

import flash.display.*

import flash.events.*;

public class StageListeners extends Sprite {

private var _mc:Sprite;

private var mcStage:Stage;

public function StageListeners(_mc:Sprite){

this._mc = _mc;

mcStage = _mc.stage;

addStageListener();

}//StageListeners

public function addStageListener() {

mcStage.scaleMode = StageScaleMode.NO_SCALE;

mcStage.align = StageAlign.TOP_LEFT;

mcStage.addEventListener(Event.RESIZE, resizeHandler);

}//addStageListener

private function resizeHandler(event:Event):void {

trace(“stageWidth: “+mcStage.stageWidth);

trace(“stageHeight: “+mcStage.stageHeight);

//aligned center

_mc.x = mcStage.stageWidth/2;

_mc.y = mcStage.stageHeight/2;

//or if aligned left

_mc.x = 0;

_mc.width = mcStage.stageWidth;

var scaleAmountX:Number = _mc.scaleX;

_mc.scaleY = scaleAmountX; //keep proportional

}//resizeHandler

}//class

}//package

//////////////////////instantiate with:

var bgStageListener:StageListeners = new StageListeners(resizeBg);