> How can I prevent the user from scrolling in that situation,
> like it is done in the LookupCombo ?

You may be able to use the OnGetCanScroll handler of the dataset.

Note that there was some discussion about this event handler a few
weeks ago, that relate to the fact that any edit/insert taking place
on the grid will be posted before this event is called. This issue
has not yet been resolved.

From your description I suspect this will not impact what you are
doing.

Geoff Worboys
Telesis Computing