If you would like to ask the user if he wants to change something before performing the actual change you can use the following:
sender, GridViewCellEventArgs e)
var editor = e.ActiveEditor;
sender, ValueChangingEventArgs e)
// ask here
If this is not a good a solution i will try to see what's happening with the CellValidating and the CancelEdit().
Hope this helps, if you have any other questions or comments, please let me know,
Telerik WinForms MVP