Subject: bug#10382: 24.0.92; gratuituous `file-supersession' error for `menu-bar-update-hook'

From: "Drew Adams" <[email-masked]>
Date: Tue, 27 Dec 2011 13:41:41 -0800

1. I visit a file.  I thumbify its (one-window) frame, which means that
I shrink the frame and remove its menu bar.  (Menu-bar mode is on,
globally.)
 
2. I change the file contents on disk (e.g. with another Emacs session).
 
3. I dethumbify the frame visiting the file, which means that I restore
its original size and add back the menu bar. I do this by hitting a key.
 
4. The screen goes blank: all frames are blank.  I see the hourglass
prompt (IIRC), but nothing else indicates that Emacs is doing anything.
 
5. I hit C-g.  I hit C-g again (the first does nothing, apparently).
 
6. The content of all frames reappears, and I see now this message in
the echo area (could not see anything there before, because all
frames were blank):
 
Error in menu-bar-update-hook (imenu-update-menubar): (file-supersession File
changed on disk c:/drews-lisp-20/bookmark+-1.el)
 
[Note, that is all on one line - a very long error message!]
 
7. I look in buffer `*Messages*' and see this:
 
bookmark+-bmu.el changed on disk; really edit the buffer? (y, n, r or C-h)  [2
times]
Error in menu-bar-update-hook (imenu-update-menubar): (file-supersession File
changed on disk c:/drews-lisp-20/bookmark+-bmu.el)
 
8. Apparently I should have seen the question about editing.  Emacs
was apparently waiting for a response from me.  But I could see
nothing at all, anywhere (all buffers blanked out).
 
Seems like maybe there is a redisplay problem here?
 
9. Also, I did NOT try to edit the buffer (e.g. type a character).  I
simply hit a key that dethumbifies the frame.  Of course, that changes
frame parameters, but it does not in any way try to change ("edit") the
buffer.  So I don't see why I should get the question at all at that
point.
 
In GNU Emacs 24.0.92.1 (i386-mingw-nt5.1.2600) of 2011-12-06 on MARVIN
 Windowing system distributor `Microsoft Corp.', version 5.1.2600
 configured using `configure --with-gcc (4.6) --no-opt --cflags
 -ID:/devel/emacs/libs/libXpm-3.5.8/include
 -ID:/devel/emacs/libs/libXpm-3.5.8/src
 -ID:/devel/emacs/libs/libpng-dev_1.4.3-1/include
 -ID:/devel/emacs/libs/zlib-dev_1.2.5-2/include
 -ID:/devel/emacs/libs/giflib-4.1.4-1/include
 -ID:/devel/emacs/libs/jpeg-6b-4/include
 -ID:/devel/emacs/libs/tiff-3.8.2-1/include
 -ID:/devel/emacs/libs/gnutls-2.10.1/include --ldflags
 -LD:/devel/emacs/libs/gnutls-2.10.1/lib'