             stepSize = Math.abs(viewport.getHorizontalScrollPositionDelta(
                 (increase) ? NavigationUnit.RIGHT : NavigationUnit.LEFT));
         }
-        super.step(increase);
+        super.changeValueByStep(increase);
         if (viewport)
             stepSize = oldStepSize;
     }   

     *  @playerversion AIR 1.5
     *  @productversion Flex 4
     */
    override public function page(increase:Boolean = true):void
    {
        var oldPageSize:Number;
        if (viewport)
        {
            // Want to use ScrollBar's page() implementation to get the same
            // animated behavior for scrollbars with and without viewports.
            // For now, just change pageSize temporarily and call the superclass
            // implementation.

    }
    

    /**
     *  If <code>viewport</code> is not null, 
     *  change the horizontal scroll position for page up or page down by 
