      */
     private var steppingDown:Boolean;
     private var steppingUp:Boolean;
+	private var isStepping:Boolean;
 
     /**
      * @private

        systemManager.getSandboxRoot().removeEventListener(SandboxMouseEvent.MOUSE_UP_SOMEWHERE, 
            track_mouseUpHandler);

        if (trackScrollTimer)
            trackScrollTimer.reset();
            
        if (getStyle("smoothScrolling") && !animatingSinglePage)
        {
            if (animator.isPlaying)
            {
                animationEndHandler(animator);
            }
            // Stop it regardless, in case the animation is startDelayed and
            // thus not 'playing', but still active
            animator.stop();
        }
    }

    /**

    mx_internal function viewportVerticalScrollPositionChangeHandler(event:PropertyChangeEvent):void
    {
    }   
	
	//---------------------------------
	// Thumb dragging handlers
	//---------------------------------
	
	/**
	 *  @private
	 */
	override protected function thumb_mouseDownHandler(event:MouseEvent) : void
	{
		// Stop animation before thumb dragging
		if (animatingSinglePage)
		{
			animationEndHandler(animator);
			animator.stop();
		}
		
		super.thumb_mouseDownHandler(event);
	}
	
    //---------------------------------
    // Mouse up/down handlers
    //---------------------------------
