Functional items are static rows in the grid that perform some function.
The Pager is a row that contains the paging navigation controls. To have the grid divide its data into pages, set the grid's AllowPaging property to True.
You can define the style of the Pager Row using the RadGrid property builder or the PagerStyle section of the RadGrid property pane.
The CommandItem is a place holder for commands that can perform some action on the items in the grid. Commands can be processed on the selected items, or on all items in the grid. See the Command reference topic for details about the available commands you can add to the CommndItem.
The GridStatusBarItem appears below all other items in the grid and displays the information about the current grid status. This item is intended primarily for use when RadGrid is used with RadAjaxManager to indicate when RadGrid is performing asynchronous AJAX requests. To show the status bar item, set the grid's ShowStatusBar property to True.
You should have a data source assigned in order to use RadGrid with a status bar.