In zwei in System 78.58, ZMail 38.5, Programmer's Apprentice 21.4, Dungeon 2.1, Detective 2.2, microcode 836, Sorcerer's Apprentice, on Lisp Machine Twenty-two: If you do c-m-X while in an m-X, c- loses next time (ie puts you in m-X instead of c-m-X.)