You can attach to the FieldFilterEditorCreated event of the grid. The event arguments will contain the instance of the field filter editor being created, in this case a StringFilterEditor. You can find the check-box with the ChildrenOfType<T> method and set its Visibility to false, if you know that it will not work.
Let me know if there are problems with this approach.
the Telerik team
Registration for Q1 2011 What’s New Webinar Week is now open. Mark your calendar for the week starting March 21st and book your seat
for a walk through all the exciting stuff we ship with the new release!