Undo Container Close Gap

It would be good if  Container Close Gap were immediately undoable.

Two reasons:

1.   for it's own sake, in case you want to undo it (like anything else)
2.   because until one is thoroughly trained not to ever hit Ctrl-Z after Container Close Gap, one may do so at any time and this will undo something, no doubt something you did not intend.  This can make a real mess!   One is expecting a nice clean predictable instant Undo (of Container Close Gap), and instead gets a blasted into the past, discarding previous work that was not intended to be discarded.