use the EDIT > UNDO to go back. I'm not sure, but I think it drops the edit list when you close the program so get it before you shut it down. Also.... if you've done a few other things before you catch the mistake and use the EDIT>UNDO you will have to redo the things after the mistake.
So there IS an undo!! Thank you!!
I keep telling myself, I just have to learn how BIAB thinks and I'll be okay, lol...