      *
      *  <p>If <code>viewport</code> is null, 
      *  change the scroll position for line up or line down by calling 
-     *  the <code>step()</code> method.</p>
+     *  the <code>changeValueByStep()</code> method.</p>
      *
      *  @param increase Whether the line scoll is up (<code>true</code>) or
      *  down (<code>false</code>). 
      * 
-     *  @see mx.components.baseClasses.TrackBase#step()
+     *  @see mx.components.baseClasses.TrackBase#changeValueByStep()
      *  @see mx.components.baseClasses.TrackBase#setValue()
      *  @see spark.core.IViewport
      *  @see spark.core.IViewport#horizontalScrollPosition

            pageSize = Math.abs(viewport.getHorizontalScrollPositionDelta(
                (increase) ? NavigationUnit.PAGE_RIGHT : NavigationUnit.PAGE_LEFT));
        }
        super.page(increase);
        if (viewport)
            pageSize = oldPageSize;
    }

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