bug#8789: 23.3; debug backtrace buffer changes window on step-through

[Pete Beardmore]

Hi,

A couple of my frame window layouts cause the emacs debugger's  
backtrace buffer to cycle between several windows when stepping  
through code, making it very difficult to focus.

Please follow the minimal steps below to re-produce this undesirable  
behaviour, also confirmed as present by another user (#emacs  
'off-by-1') in a 'relatively recent git version'..

emacs -q
C-x 3
C-x 2
M-x debug-on-entry RET
apropos RET
M-x apropos RET
x RET
d RET
d RET

..you should see the buffer alternate windows on each step through the code.

Thanks,

Pete.


In GNU Emacs 23.3.1 (i486-slackware-linux-gnu, GTK+ Version 2.24.1)
 of 2011-03-12 on midas
Windowing system distributor `The X.Org Foundation', version 11.0.10899906
configured using `configure  '--prefix=/usr' '--sysconfdir=/etc'  
'--localstatedir=/var' '--program-prefix=' '--program-suffix='  
'--mandir=/usr/man' '--infodir=/usr/info' '--enable-static=no'  
'--enable-shared=yes' '--with-x' '--with-x-toolkit=gtk'  
'--build=i486-slackware-linux' 'build_alias=i486-slackware-linux'  
'CFLAGS=-O2 -march=i486 -mtune=i686''

Important settings:
  value of $LC_ALL: nil
  value of $LC_COLLATE: C
  value of $LC_CTYPE: nil
  value of $LC_MESSAGES: nil
  value of $LC_MONETARY: nil
  value of $LC_NUMERIC: nil
  value of $LC_TIME: nil
  value of $LANG: en_GB.utf8
  value of $XMODIFIERS: nil
  locale-coding-system: utf-8-unix
  default enable-multibyte-characters: t

Major mode: Fundamental

Minor modes in effect:
  tooltip-mode: t
  mouse-wheel-mode: t
  tool-bar-mode: t
  menu-bar-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  blink-cursor-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t
  line-number-mode: t
  transient-mark-mode: t

Recent input:
<help-echo> <down-mouse-1> <mouse-movement> <mouse-1>
C-x 3 C-x 2 M-x d e b u g - o n - e n t r y <return>
a p r o p o s <return> M-x a p r o p o <tab> <return> x
<return> d d M-x C-g
C-] M-x r e p o r t <tab> <return>

Recent messages:
For information about GNU Emacs and the GNU system, type C-h C-a.
Loading apropos...done
Entering debugger...
Proceeding, will debug on next eval or call.
Entering debugger...
Proceeding, will debug on next eval or call.
Entering debugger...
Quit
Quit

Load-path shadows:
./cedet/cedet-ediff hides ./cedet-1.1bzr8044/cedet-ediff
./cedet/cedet-update-version hides ./cedet-1.1bzr8044/cedet-update-version
./cedet/cedet-build hides ./cedet-1.1bzr8044/cedet-build
./cedet/cedet-update-changelog hides ./cedet-1.1bzr8044/cedet-update-changelog
/usr/share/emacs/site-lisp/t-mouse hides /usr/share/emacs/23.3/lisp/t-mouse

Features:
(shadow sort mail-extr message idna sendmail regexp-opt ecomplete rfc822
mml mml-sec password-cache mm-decode mm-bodies mm-encode mailcap
mail-parse rfc2231 rfc2047 rfc2045 qp ietf-drums mailabbrev nnheader
gnus-util netrc time-date mm-util mail-prsvr gmm-utils wid-edit
mailheader canlock sha1 hex-util hashcash mail-utils emacsbug help-mode
easymenu view apropos debug tooltip ediff-hook vc-hooks lisp-float-type
mwheel x-win x-dnd font-setting tool-bar dnd fontset image fringe
lisp-mode register page menu-bar rfn-eshadow timer select scroll-bar
mldrag mouse jit-lock font-lock syntax facemenu font-core frame cham
georgian utf-8-lang misc-lang vietnamese tibetan thai tai-viet lao
korean japanese hebrew greek romanian slovak czech european ethiopic
indian cyrillic chinese case-table epa-hook jka-cmpr-hook help simple
abbrev loaddefs button minibuffer faces cus-face files text-properties
overlay md5 base64 format env code-pages mule custom widget
hashtable-print-readable backquote make-network-process dbusbind
font-render-setting gtk x-toolkit x multi-tty emacs)