 
 import mx.core.IViewport;
 import mx.core.UIComponent;
+import mx.core.ScrollUnit;
 import mx.events.FlexEvent;
 import mx.events.TextOperationEvent;
 import mx.utils.TextUtil;

    //----------------------------------

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

            
        switch (unit)
        {
            case ScrollUnit.UP:
                return (scrollR.x <= 0) ? 0 : -1;
                
            case ScrollUnit.DOWN:
                return (scrollR.x >= maxDelta) ? 0 : 1;
                
            case ScrollUnit.PAGE_LEFT:
                return Math.max(minDelta, -scrollR.width);
                
            case ScrollUnit.PAGE_RIGHT:
                return Math.min(maxDelta, scrollR.width);
                
            case ScrollUnit.HOME: 
                return minDelta;
                
            case ScrollUnit.END: 
                return maxDelta;
                
            default:
