     
     /**
      *  @private
+     */
+    override mx_internal function get virtualLayoutSupported():Boolean
+    {
+        return false
+    }
+    
+    /**
+     *  @private
      *  Used to set new column widths before laying out the elements.
      *  Used by FormItemLayout to set column widths provided by the
      *  Form.

        var row:ConstraintRow;
        var hasContentSize:Boolean = false;
        var hasPercentSize:Boolean = false;
        var rowHeights:Vector.<Number> = new Vector.<Number>();
        
        // Reset content size rows to 0.
        for (i = 0; i < numRows; i++)
        {
            row = _constraintRows[i];

            }
            else if (!isNaN(row.explicitHeight))
            {
                var h:Number = row.explicitHeight;
                
                if (!isNaN(row.minHeight))
                    h = Math.max(h, row.minHeight);
