 {
 import flash.geom.Point;
 
-import mx.core.IInvalidating;
 import mx.core.IUIComponent;
 import mx.core.ScrollPolicy;
 import mx.utils.MatrixUtil;


    /**
     * @private
     *  Computes the union of the preferred size of the visible 
     *  scrollbars and the viewport.  
     * 
     *  This becomes the ScrollerSkin's measuredWidth,Height.
     *    
     *  The ScrollerSkin's minimum size is only big enough to 
     *  acccomodate the visible scrollbars.
     * 
     *  The viewport does not contribute to the minimum size unless its
     *  explicit size has been set.
     */
    override public function measure():void
    {
        var scroller:Scroller = getScroller();
        if (!scroller) 
            return;
            
        var minViewportInset:Number = scroller.minViewportInset;
        var measuredW:Number = minViewportInset;
        var measuredH:Number = minViewportInset;
        
        var hsb:ScrollBar = scroller.horizontalScrollBar;
        var showHSB:Boolean = false;
        var hAuto:Boolean = false;
        switch(scroller.getStyle("horizontalScrollPolicy")) 
        {
            case ScrollPolicy.ON: 
                if (hsb) showHSB = true; 
                break;
            case ScrollPolicy.AUTO: 
                if (hsb) showHSB = hsb.visible;
                hAuto = true;
                break;
        } 

        var vsb:ScrollBar = scroller.verticalScrollBar;
        var showVSB:Boolean = false;
        var vAuto:Boolean = false;
        switch(scroller.getStyle("verticalScrollPolicy")) 
        {
           case ScrollPolicy.ON: 
                if (vsb) showVSB = true; 
                break;
            case ScrollPolicy.AUTO: 
                if (vsb) showVSB = vsb.visible;
                vAuto = true;
                break;
        }
        
        measuredH += (showHSB) ? hsbRequiredHeight() : minViewportInset;
        measuredW += (showVSB) ? vsbRequiredWidth() : minViewportInset;

        g.measuredMinWidth = Math.ceil(minW); 
        g.measuredMinHeight = Math.ceil(minH);
    }

    /** 
     *  @private
     *  Arrange the viewport and scrollbars conventionally within
