DockIcon  - AS3

     icon.bitmaps = new Array(icon16x16.bitmapData, icon128x128.bitmapData);
     

 package {
    import flash.desktop.DockIcon;
    import flash.desktop.NativeApplication;
    import flash.display.Loader;
    import flash.display.NativeMenu;
    import flash.display.NativeMenuItem;
    import flash.display.Sprite;
    import flash.events.Event;
    import flash.events.TimerEvent;
    import flash.net.URLRequest;
    import flash.utils.Timer;

    public class AnimatedDockIcon extends Sprite
    {
        private var imageURLs:Array =  ['gfx/frame01.png',
                                        'gfx/frame02.png',
                                        'gfx/frame03.png',
                                        'gfx/frame04.png'];
        
        private var images:Array = new Array();
        private var animTimer:Timer = new Timer(100);
                                        
        public function AnimatedDockIcon()
        {
            NativeApplication.nativeApplication.autoExit = false;
            
            addEventListener(Event.COMPLETE, loadImages);
            loadImages();
            
            animTimer.addEventListener(TimerEvent.TIMER,advanceFrame);
            addMenu();
            stage.nativeWindow.close();
        }
        
        private function addMenu():void{
            var menu:NativeMenu = new NativeMenu();
            var start:NativeMenuItem = menu.addItem(new NativeMenuItem("Start animation"));
            var stop:NativeMenuItem = menu.addItem(new NativeMenuItem("Stop animation"));
            start.addEventListener(Event.SELECT, startTimer);
            stop.addEventListener(Event.SELECT, stopTimer);
            
            var dockIcon:DockIcon =    NativeApplication.nativeApplication.icon as DockIcon;
            dockIcon.menu = menu;
        }
        
        private function startTimer(event:Event):void{
            animTimer.start();
        }

        private function stopTimer(event:Event):void{
            animTimer.stop();
        }

        private var currentFrame:int = 0;
        private function advanceFrame(event:Event):void{
            if(currentFrame < images.length){
                currentFrame++;
            } else {
                currentFrame = 0;
            }
            NativeApplication.nativeApplication.icon.bitmaps = [images[currentFrame]];
        }
        

        private function loadImages(event:Event = null):void{
            if(event != null){
                images.push(event.target.content.bitmapData);
            }
            if(imageURLs.length > 0){
                var urlString:String = imageURLs.pop();
                var loader:Loader = new Loader();
                loader.contentLoaderInfo.addEventListener(Event.COMPLETE, loadImages, false, 0, true);
                loader.load(new URLRequest(urlString));
            } else {
                var complete:Event = new Event(Event.COMPLETE,false,false);
                dispatchEvent(complete);
            }
        }
    }
}