bug#510: 23.0.60; "There is nothing to follow here" in apropos-variable

[Sven Joachim <svenjoac@gmx.de>]

In an *Apropos* buffer created by M-x apropos-variable it is not
possible to go to the variables' definitions by pressing RET with point
on them, I got the error message in the subject.

Additionally, pressing TAB in the *Apropos* buffer lets Emacs use 100%
CPU until C-g is pressed:

,----
| Debugger entered--Lisp error: (quit)
|   button-at(295)
|   next-button(258)
|   forward-button(1 1 1)
|   call-interactively(forward-button nil nil)
`----


In GNU Emacs 23.0.60.1 (i486-pc-linux-gnu, GTK+ Version 2.12.10)
 of 2008-06-30 on debian, modified by Debian
 (emacs-snapshot package, version 1:20080630-1)
Windowing system distributor `The X.Org Foundation', version 11.0.10402000
configured using `configure  '--build' 'i486-linux-gnu' '--host' 'i486-linux-gnu' '--prefix=/usr' '--sharedstatedir=/var/lib' '--libexecdir=/usr/lib' '--localstatedir=/var' '--infodir=/usr/share/info' '--mandir=/usr/share/man' '--with-pop=yes' '--enable-locallisppath=/etc/emacs-snapshot:/etc/emacs:/usr/local/share/emacs/23.0.60/site-lisp:/usr/local/share/emacs/site-lisp:/usr/share/emacs/23.0.60/site-lisp:/usr/share/emacs/site-lisp' '--with-x=yes' '--with-x-toolkit=gtk' 'build_alias=i486-linux-gnu' 'host_alias=i486-linux-gnu' 'CFLAGS=-DDEBIAN -DSITELOAD_PURESIZE_EXTRA=5000 -g -O2' 'LDFLAGS=-g -Wl,--as-needed' 'CPPFLAGS=''

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: de_DE.UTF-8
  value of $XMODIFIERS: nil
  locale-coding-system: utf-8-unix
  default-enable-multibyte-characters: t

Major mode: Apropos

Minor modes in effect:
  shell-dirtrack-mode: t
  display-time-mode: t
  auto-image-file-mode: t
  show-paren-mode: t
  tooltip-mode: t
  mouse-wheel-mode: t
  menu-bar-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  font-lock-mode: t
  global-auto-composition-mode: t
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t
  temp-buffer-resize-mode: t
  column-number-mode: t
  line-number-mode: t
  transient-mark-mode: t

Recent input:
<left> <left> <left> <left> <left> t h e SPC <end> 
SPC i n SPC m i n i b u f f e r . e l SPC <backspace> 
. SPC SPC S j <backspace> h o u l d SPC t h a t SPC 
l i s t SPC i n c l u d e SPC y <backspace> c y g w 
i n SPC a s SPC w e l l ? <return> <return> S v e n 
C-x C-s C-c a <up> <right> <right> <right> <right> 
<right> <right> <right> <right> <right> <right> <right> 
<right> <right> <right> C-k <return> C-x o <down> <down> 
<down> <down> <down> <down> <down> <down> <down> <down> 
<down> <down> <down> <down> <down> <down> <down> <down> 
<down> <down> <down> <return> <down> <down> <down> 
<return> <up> <down> <down> <down> <return> <up> <up> 
<up> <up> <up> <up> <up> <up> <up> <up> <up> <up> <up> 
<up> <up> <up> <up> <up> <up> <up> <up> <up> <up> <up> 
<up> <up> <up> <up> <up> <down> <down> <down> <down> 
<down> <return> C-c a <up> <up> <return> <down> <down> 
<down> <down> <down> <down> <down> <down> <down> <down> 
<down> <down> <down> <up> <up> <up> <return> C-x 0 
C-h C-v <up> <return> C-x o <down> <down> <down> <down> 
<down> <down> <down> <down> <down> <down> <down> <down> 
<up> <up> <right> <right> <return> C-x 0 q <up> <up> 
<up> <end> <left> <left> d e f c u s t o m SPC <end> 
M-q <down> <down> <down> <up> <up> <up> C-x C-s <right> 
<right> C-c C-s SPC SPC SPC SPC SPC y M-x t o g g l 
e - d e b <tab> e r r <tab> <return> C-h C-v <up> <return> 
C-x o <tab> <return> q M-x r e p o e <backspace> r 
t - e m a <tab> b <tab> <return>

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