[NaB] [2594] Undo leaves hole in wall when undoing window placement

Undo occasionally leaves a hole in the wall when you are undoing windows. Probably an old bug. Still exists.

[edit] Ah, so when you place the next window, it updates the wall and patches it up. So it’s just the update that’s a little slow. (also note, gridlines are totally lost when this wall is highlighted)