Re: undo in loaddefs.el buffer

[Luc Teirlinck <teirllm@dms.auburn.edu>]

Richard Stallman wrote (in response to Juri Linkov):

       And what is unusual for such yes-no prompts is that it can't be
       interrupted with C-g.  Typing C-g pops up an unwanted X popup menu.

   C-g normally should quit out of this question.  Why not in this case?
   This too may be fixable, but only with more precise information.

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).

Obvious question to Juri:  Which toolkit do you use?

Everything below concerns the behavior with the default Lucid toolkit.

Strange things happen with popup menus, at least using the default
Lucid toolkit.

Do `emacs -q', M-x ielm then:

(let (last-nonmenu-event) (yes-or-no-p "prompt"))

Now if you press any key, regular or modifier, say "a", Control,
Shift, nil is returned, like if you answered "No".  This appears to be
an obvious bug.  For the particular application we are worried about,
this is particularly bad, because "No" is the dangerous answer, the
one that might make Emacs crash.

If we repeat the experiment in 21.3, we see that the bug is not
present there.  However, there is another bug.  If we click the mouse
anywhere inside the Emacs frame, but outside the "Yes" button, nil is
returned.  This is also a bug, which does _not_ occur in current CVS.
This seems to be a case of introducing one bug by fixing another.

Sincerely,

Luc.