     }
     
     /**
-     *  Implicitly update the viewport's verticalScrollPosition per the
-     *  specified scrolling unit, by setting the scrollbar's value.
-     *
-     *  @private
-     */
-    private function updateViewportHSP(scrollUnit:uint):void
-    {
-        var delta:Number = viewport.getHorizontalScrollPositionDelta(scrollUnit);
-        setValue(viewport.horizontalScrollPosition + delta);
-    }
-    
-    /**
      *  If <code>viewport</code> is not null, 
      *  change the horizontal scroll position for page up or page down by 
      *  scrolling the viewport.

     */
    override public function page(increase:Boolean = true):void
    {
        if (!viewport)
            super.page(increase);
        else
            updateViewportHSP((increase) ? ScrollUnit.PAGE_RIGHT : ScrollUnit.PAGE_LEFT);
    }
    
    /**

     */
    override public function step(increase:Boolean = true):void
    {
        var oldStepSize:Number;
        if (viewport)
        {
            // Want to use ScrollBar's step() implementation to get the same
            // animated behavior for scrollbars with and without viewports.
            // For now, just change pageSize temporarily and call the superclass
            // implementation.
            oldStepSize = stepSize;
            stepSize = Math.abs(viewport.getHorizontalScrollPositionDelta(
                (increase) ? ScrollUnit.RIGHT : ScrollUnit.LEFT));
        }
        super.step(increase);
        if (viewport)
            stepSize = oldStepSize;
    }   
    
    /**
