Re: undo in loaddefs.el buffer

[Richard Stallman]

    This might be toolkit dependent.  (At least for popup menus).  If the
    answer gets asked in the minibuffer, quitting works normally (at least
    for me).

We recently looked at the code in xmenu.c that pops up dialogs,
and concluded it could safely run timers.  If timers are safe,
quitting must be safe.  But there could be some case in which
it doesn't allow quitting.  We should investigate that.

Meanwhile, I am not sure it is right for this question to appear as a
pop-up menu.  yes-or-no-p uses a pop-up menu wen the current command
was invoked with the mouse, and that is right when the command itself
asks the question, but it may not be right for this.  It would be
easy to change undo-outer-limit-truncate to use the minibuffer
unconditionally.