package as3
{
	import flash.display.Sprite;
	import flash.events.Event;
	
	public class SpriteSub extends Sprite
	{
		function SpriteSub()
		{
			this.addEventListener(Event.ADDED_TO_STAGE, addedToStage);
		}
		
		protected function addedToStage(e:Event):void
		{
			trace(this.stage);
		}
	}
}

//fla
import as3.SpriteSub;
var spriteSub:SpriteSub = new SpriteSub();
addChild(spriteSub);