      *  @see mx.components.baseClasses.FxTrackBase#setValue()
      *  @see mx.core.IViewport
      *  @see mx.core.IViewport#horizontalScrollPosition
-     *  @see mx.core.IViewport#horizontalScrollPositionDelta()
+     *  @see mx.core.IViewport#getHorizontalScrollPositionDelta()
      */
     override public function page(increase:Boolean = true):void
     {
         if (!viewport)
             super.page(increase);
         else
-            updateViewportHSP((increase) ? Keyboard.PAGE_DOWN : Keyboard.PAGE_UP);
+            updateViewportHSP((increase) ? ScrollUnit.PAGE_RIGHT : ScrollUnit.PAGE_LEFT);
     }
     
     /**

     *
     *  @private
     */
    private function updateViewportHSP(unit:uint):void
    {
        var delta:Number = viewport.horizontalScrollPositionDelta(unit);
        setValue(viewport.horizontalScrollPosition + delta);
    }
    

     *  change the horizontal scroll position for line up or line down by 
     *  scrolling the viewport.
     *  This method calculates the amount to scroll by calling the 
     *  <code>IViewport.getHorizontalScrollPositionDelta()</code> method 
     *  with either <code>flash.ui.Keyboard.RIGHT</code> 
     *  or <code>flash.ui.Keyboard.LEFT</code>.
     *  It then calls the <code>setValue()</code> method to 
