if(!modalWindowClass){    
	        g.clear();
	        g.beginFill(c, 100);
	        g.drawRect(s.x, s.y, s.width, s.height);
	        g.endFill();
        }

<?xml version="1.0" encoding="utf-8"?>
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" layout="absolute" width="300" height="300" applicationComplete="init();">
 
	<mx:Script>
		<![CDATA[
			import mx.controls.Alert;
			import mx.managers.PopUpManager;
 
			import mx.managers.PopUpManagerImpl;
 
			import mx.core.mx_internal;
 
			use namespace mx_internal;
 
			private function init():void{
				var impl:PopUpManagerImpl=PopUpManagerImpl.getInstance() as PopUpManagerImpl;
				impl.modalWindowClass=CustomPopUpShield;
			}
 
			private function openPopUp():void{
 
 
				Alert.show("hehe","Try pop up");
			}
 
		]]>
	</mx:Script>
 
	<mx:Style>
		/*With these settings I practically turned off the default behavior. The transparency have to be 1, 
		because it will be the transparency for the whole shield.(with 0 we would not see anything)*/
		Application{
			horizontalGap:"0";
    		modalTransparency:"1";
    		modalTransparencyBlur:"0";
    		modalTransparencyColor:"#ffffff";
    		modalTransparencyDuration:"0";
		}
 
	</mx:Style>
 
	<mx:HBox horizontalGap="0" height="100%">
		<mx:VBox width="60" height="100%">
			<mx:Button label="Click!" click="openPopUp()"/>
			<mx:Button label="Click!" click="openPopUp()"/>
			<mx:Button label="Click!" click="openPopUp()"/>
			<mx:Button label="Click!" click="openPopUp()"/>
			<mx:Button label="Click!" click="openPopUp()"/>
			<mx:Button label="Click!" click="openPopUp()"/>
			<mx:Button label="Click!" click="openPopUp()"/>
		</mx:VBox>
		<mx:Canvas width="240" height="100%" backgroundColor="#0000ff">
			<mx:Button x="102" y="47" label="click" click="openPopUp()"/>
 
		</mx:Canvas>
	</mx:HBox>
</mx:Application>

package
{
	import flash.display.Sprite;
	import flash.filters.BlurFilter;
	import flash.filters.GlowFilter;
	import flash.geom.Rectangle;
 
	import gs.TweenMax;
	import gs.easing.Back;
 
	import mx.core.Application;
 
	public class CustomPopUpShield extends Sprite
	{
 
		private var _base:Sprite;//this will be an invisible shape over the whole screen to prevent clicking on the buttons
		private var _animatingContent:Sprite;//this will animate
 
		override public function CustomPopUpShield(){
			super();
 
			var sc:Rectangle=Application.application.screen;
 
			_base=new Sprite();
			_base.graphics.beginFill(0x000000,0);
			_base.graphics.drawRect(0,0,sc.width,sc.height);
			_base.graphics.endFill();
			this.addChild(_base);
 
			_animatingContent=new Sprite();
			_animatingContent.graphics.beginFill(0x00ff00,0.4);
			_animatingContent.graphics.drawRect(60,0,sc.width,sc.height);
			_animatingContent.graphics.endFill();
			this.addChild(_animatingContent);
 
			var filter:GlowFilter=new GlowFilter(4,4);
			_animatingContent.filters=new Array(filter);
 
			activate();
		}
 
		private function activate():void{
			TweenMax.to(_animatingContent, 1, {tint:0x000000,yoyo:true,ease:Back.easeIn});
		} 
 
 
 
 
 
 
	}
}