                 sep = new UIComponent();
                 sep.addChild(DisplayObject(sepSkin));
                 lines.addChild(sep);
+                UIComponentGlobals.layoutManager.validateClient(sep, true);
                 
                 separators.push(sep);
             }

            for (var i:int = 0; i < headerItems.length; i++)
                headerItems[i].setActualSize(headerItems[i].width, maxHeaderHeight);

            while (headerItems.length > colNum)
            {
                // remove extra columns
                extraItem = headerItems.pop();
                removeChild(DisplayObject(extraItem));
            }
        }
        var headerBG:UIComponent =

            lines.removeChildAt(lines.numChildren - 1);
            separators.pop();
        }
        UIComponentGlobals.layoutManager.validateClient(lines, true);
    }
    
     /**
