How to resize menu window in Xubuntu 18.04?

I have accidentally pressed some Alt+f.. key and now my menu window (the one that opens when I click on the top left corner) is full size. Tried various settings and I'm more confused. Originally I changed the Alt+f4 to be able to use it in dosbox lotus-123 for undo function, and it works there. I also set Shift+Alt+f4 to resize window - and it does work for any open window except for this menu window. So the short question is: how to resize the open menu window? This is Xubuntu 18.04, I think xfce something.