Thanks. I'll give it a shot.
Actually, I did give it a shot, but as I was in the middle of a ad-hoc backup, the GUI closed, except for a window saying that it would close when the backup was completed. Now, of course, I can't get the GUI back.
I'll try to remember this next time, but I would suggest an alert/question dialog before exiting when ad-hoc actions are still in progress.