codice:
var FullScreenStatus:Boolean;
init();
//fullScreen_btn.visible=false
fullScreen_btn.buttonMode=true;
fullScreen_btn.stage.addEventListener(FullScreenEvent.FULL_SCREEN, attivaFullScreen);
fullScreen_btn.addEventListener(MouseEvent.CLICK, cambiaStatoFullScreen);

function init():void {
    var swfStage:Stage = fullScreen_btn.stage;
    swfStage.scaleMode = StageScaleMode.NO_SCALE;
    swfStage.align = StageAlign.TOP_LEFT;
}
function attivaFullScreen(event:FullScreenEvent):void {

    if (event.fullScreen) {
        FullScreenStatus = true;
    } else {
        FullScreenStatus = false;
    }
}
function cambiaStatoFullScreen(e:MouseEvent):void {

    if (FullScreenStatus) {
		
		fullScreen_btn.gotoAndStop(1)
		fullScreen_btn.visible=true
        fullScreen_btn.stage.displayState = StageDisplayState.NORMAL;
    } else {
        fullScreen_btn.stage.displayState = StageDisplayState.FULL_SCREEN;

fullScreen_btn.gotoAndStop(2)
	}
}