     /**
      *  @copy mx.layout.LayoutBase#getHorizontalScrollPositionDelta
      */
-    public function getHorizontalScrollPositionDelta(unit:ScrollUnit):Number
+    public function getHorizontalScrollPositionDelta(scrollUnit:uint):Number
     {
         // TBD: replace provisional implementation
         var scrollR:Rectangle = scrollRect;

        var maxDelta:Number = contentWidth - scrollR.width - scrollR.x;
        var minDelta:Number = -scrollR.x; 
            
        switch (unit)
        {
            case ScrollUnit.UP:
                return (scrollR.x <= 0) ? 0 : -1;

        
        var flowComposer:IFlowComposer = textFlow.flowComposer;
            
        switch (scrollUnit)
        {
            case ScrollUnit.UP:
            {
