<style type="text/css">body{border:0;margin:0;padding:3px;height:98% ;cursor:text;}</style> I think there is a bug in GridPanel when I have EnableDragDrop="true" and selection mode as Checkbox it un check dosen't work, if you want to
uncheck it just dosen't uncheck, and then I removed EnableDragDrop="true" and it worked
fine. 


</p>


<SelectionModel>
    <Coolite:CheckboxSelectionModel ID="chkSelectionModel" runat="server" />
</SelectionModel>
</p>
Thank
you.</p>