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

                sep = new UIComponent();
                sep.addChild(DisplayObject(sepSkin));
                lines.addChild(sep);
                
                separators.push(sep);
            }

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

            for (i = 0; i < oldHeaderItems.length; i++)
            {
                item = oldHeaderItems[i];
                if (item && headerItems.indexOf(item) == -1)
                {
                    // if it is parented by us, remove it (could be in lockedColumns header)
                    if (item.parent == this)
                        removeChild(DisplayObject(item));
                }
            }
            while (headerItems.length > colNum)
            {
                // remove extra columns
                extraItem = headerItems.pop();
                // if it is parented by us, remove it (could be in lockedColumns header)
                if (extraItem.parent == this)
                    removeChild(DisplayObject(extraItem));
            }
        }
        var headerBG:UIComponent =
