Here is a sample script I worte to create an autohiding toolbar. Its a very simple application which shows the toolbar when the mouse moves over the panel, and hides the toolbar when there is no activity for 2 seconds.

   

     layout="absolute" 
    creationComplete="onCreationComplete()"
    mouseMove="onMouseMove(event)"
    >
    
       
                   import flash.events.TimerEvent;
          import flash.utils.Timer;       
          //setup the application timer to fire off a timer event every two seconds - 
          //alter this to how long you want the toolbar visible for
          public  var appTimer:Timer = new Timer(2000, 0);  
           
          // Setup the visibility property for the toolbar
          [Bindable] private var toolbarVisible:Boolean = true;      
          
          public function onCreationComplete():void{
            //add the timer event and start the timer
            this.appTimer.addEventListener("timer", this.timerHandler);  
            this.appTimer.start();   
          }
        
          public function timerHandler(event:TimerEvent):void {
            // when the timer fires its event hide the toolbar
            toolbarVisible = false;
          }
  
          public function onMouseMove(event:MouseEvent):void {
            //whenever the mouse moves over the application, show the
           // toolbar and restart the timer restart the timer
            toolbarVisible = true;
            this.appTimer.reset();
           this.appTimer.start();
          }
        
           ]]>