[Sprynk]

package {
	import flash.display.*;
	import flash.events.MouseEvent;
 
	public class my_fullScr extends Sprite {
 
		function my_fullScr() {
			stage.addEventListener(MouseEvent.CLICK, startfullScr);
		}
		function startfullScr(event:MouseEvent):void {
				stage.displayState = StageDisplayState.FULL_SCREEN;
				trace(stage.displayState);//возвращает null			
		}
	}
}