     override protected function focusOutHandler(event:FocusEvent):void
     {
         super.focusOutHandler(event);
-        
-        removeSystemHandlers(MouseEvent.MOUSE_WHEEL, system_mouseWheelHandler, stage_mouseWheelHandler);
+        systemManager.getSandboxRoot().removeEventListener(MouseEvent.MOUSE_WHEEL, system_mouseWheelHandler);
     }
     
     /**

    override protected function focusInHandler(event:FocusEvent):void
    {
        super.focusInHandler(event);
        
        addSystemHandlers(MouseEvent.MOUSE_WHEEL, system_mouseWheelHandler, stage_mouseWheelHandler);
    }
    
    /**

     *  the mouse down point in clickOffset.
     */
    protected function thumb_mouseDownHandler(event:MouseEvent):void
    {        
        systemManager.getSandboxRoot().addEventListener(MouseEvent.MOUSE_MOVE, 
            system_mouseMoveHandler, true);
        systemManager.getSandboxRoot().addEventListener(MouseEvent.MOUSE_UP, 
            system_mouseUpHandler, true);
        systemManager.getSandboxRoot().addEventListener(SandboxMouseEvent.MOUSE_UP_SOMEWHERE, 
            system_mouseUpHandler);
        
        clickOffset = thumb.globalToLocal(new Point(event.stageX, event.stageY));
        dispatchEvent(new TrackBaseEvent(TrackBaseEvent.THUMB_PRESS));
    }

    /**
