             return;
 
         var nSteps:uint = Math.abs(event.delta);
-        var unit:ScrollUnit;
+        var scrollUnit:uint;
 
         // Scroll event.delta "steps".  If the VSB is up, scroll vertically,
         // if -only- the HSB is up then scroll horizontally.
          
         if (verticalScrollBar && verticalScrollBar.visible)
         {
-            unit = (event.delta < 0) ? ScrollUnit.DOWN : ScrollUnit.UP;
+            scrollUnit = (event.delta < 0) ? ScrollUnit.DOWN : ScrollUnit.UP;
             for(var vStep:int = 0; vStep < nSteps; vStep++)
             {
-                var vspDelta:Number = vp.getVerticalScrollPositionDelta(unit);
+                var vspDelta:Number = vp.getVerticalScrollPositionDelta(scrollUnit);
                 if (!isNaN(vspDelta))
                     vp.verticalScrollPosition += vspDelta;
             }

    {
        if (skin && viewport)
        {
            viewport.clipContent = true;
            skin.addElementAt(viewport, 0);
            viewport.addEventListener(PropertyChangeEvent.PROPERTY_CHANGE, viewport_propertyChangeHandler);
            addSystemHandlers(MouseEvent.MOUSE_WHEEL, mouseWheelHandler, mouseWheelHandler);            
        }
        if (verticalScrollBar)
            verticalScrollBar.viewport = viewport;

            verticalScrollBar.viewport = null;        
        if (skin && viewport)
        {
            viewport.clipAndEnableScrolling = false;
            skin.removeElement(viewport);
            viewport.removeEventListener(PropertyChangeEvent.PROPERTY_CHANGE, viewport_propertyChangeHandler);
        }
    }
    
    /**
     *  Boolean to let us know if we need to add system handlers or not.
     *  We can't do this early on because systemManager may be null
     */ 
    private var systemListenersNeeded:Boolean = true;
    
    /**
     *  @private
     *  
     *  Need to add system handlers in commitProperties() because at 
     *  createChildren() time, systemManager may be null (it's null 
     *  when it's parent (or grandparent) isn't added to the display list yet).
     */
    override protected function commitProperties():void
    {
        if (systemListenersNeeded)
        {
            addSystemHandlers(MouseEvent.MOUSE_WHEEL, mouseWheelHandler, mouseWheelHandler);
            systemListenersNeeded = false;
        }
    }
    
