             constraintRows[i].y = totalHeight;
             totalHeight += value[i];
         }
-    }
-
-    /**
-     *  @private
-     *  This function is mx_internal so that FormItemLayout can use it
-     *  in its updateDisplayList.
-     */
-    mx_internal function checkUseVirtualLayout():void
-    {
-        if (useVirtualLayout)
-            throw new Error(ResourceManager.getInstance().getString("layout", "constraintLayoutNotVirtualized"));
     }
     
     //--------------------------------------------------------------------------

    }
    
    /**
     *  Used to set new row heights before laying out the elements.
     */ 
    protected function setRowHeights(value:Vector.<Number>):void
    {
        if (value == null)
            return;

    }
    
    /**
     *  @private
     *  This function is mx_internal so that FormItemLayout can use it
     *  in its updateDisplayList.
     */
    mx_internal function checkUseVirtualLayout():void
    {
        if (useVirtualLayout)
            throw new Error(ResourceManager.getInstance().getString("layout", "constraintLayoutNotVirtualized"));
    }
    
    /**
     *  @private
     *  Used to set new column widths before laying out the elements.
     *  Used by FormItemLayout to set column widths provided by the
     *  Form.
     */ 
    mx_internal function setColumnWidths(value:Vector.<Number>):void
    {
        if (value == null)
            return;
