bug#51629: 29.0.50; State of outline minor mode buttons not synchronized

[Matthias Meulien]

1. Set `outline-minor-mode-use-buttons' to true (I've done it through
`customize-group')

2. Enter "C-h b" and switch to the *Help* buffer

3. Toggle visibility of the first heading body using `outline-minor-mode'
keybindings "C-c @ C-t" (`outline-hide-body').

4. Observe the broken buttons state as in attached screenshot:

Note that it isn't related to being on the first heading or in a *Help*
buffer. The problem is easily reproduced when acting on any heading and
working with diff-mode buffers.

While speaking of diff-mode buffers, note that the arrows are simply not
displayed when the buffer is first displayed. Maybe this deserves a
dedicated bug?


In GNU Emacs 29.0.50 (build 1, x86_64-pc-linux-gnu, GTK+ Version 3.24.24, cairo 
version 1.16.0)
 of 2021-11-06 built on carbon
Repository revision: 6d406aee501cb6462075149683e492956ce9b7f3
Repository branch: master
Windowing system distributor 'The X.Org Foundation', version 11.0.12011000
System Description: Debian GNU/Linux 11 (bullseye)

Configured using:
 'configure --with-native-compilation'

Configured features:
ACL CAIRO DBUS FREETYPE GIF GLIB GMP GNUTLS GPM GSETTINGS HARFBUZZ JPEG
JSON LCMS2 LIBOTF LIBSELINUX LIBXML2 M17N_FLT MODULES NATIVE_COMP NOTIFY
INOTIFY PDUMPER PNG RSVG SECCOMP SOUND THREADS TIFF TOOLKIT_SCROLL_BARS
X11 XDBE XIM XPM GTK3 ZLIB

Important settings:
  value of $LANG: fr_FR.UTF-8
  value of $XMODIFIERS: @im=ibus
  locale-coding-system: utf-8-unix

Major mode: Custom

Minor modes in effect:
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  minions-mode: t
  desktop-save-mode: t
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  icomplete-mode: t
  global-so-long-mode: t
  global-auto-revert-mode: t
  auto-insert-mode: t
  tooltip-mode: t
  global-eldoc-mode: t
  show-paren-mode: t
  electric-layout-mode: t
  electric-indent-mode: t
  mouse-wheel-mode: t
  tab-bar-mode: t
  menu-bar-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  font-lock-mode: t
  blink-cursor-mode: t
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  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t
  line-number-mode: t
  indent-tabs-mode: t
  transient-mark-mode: t

Load-path shadows:
/home/matthias/.config/emacs/elpa/transient-20211029.1405/transient hides 
/usr/local/share/emacs/29.0.50/lisp/transient
/home/matthias/.config/emacs/elpa/dictionary-20201001.1727/dictionary hides 
/usr/local/share/emacs/29.0.50/lisp/net/dictionary

Features:
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gnus-topic nndraft nnmh nnfolder utf-7 epa-file gnutls network-stream
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vc-cvs vc-rcs cl-print help-fns radix-tree allout cus-start smerge-mode
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flymake project python tramp-sh tramp tramp-loaddefs trampver
tramp-integration files-x tramp-compat ls-lisp thai-util thai-word
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rng-pttrn nxml-parse nxml-ns nxml-enc xmltok nxml-util ox-latex
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european ethiopic indian cyrillic chinese composite emoji-zwj charscript
charprop case-table epa-hook jka-cmpr-hook help simple abbrev obarray
cl-preloaded nadvice button loaddefs faces cus-face macroexp files
window text-properties overlay sha1 md5 base64 format env code-pages
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inotify lcms2 dynamic-setting system-font-setting font-render-setting
cairo move-toolbar gtk x-toolkit x multi-tty make-network-process
native-compile emacs)

Memory information:
((conses 16 887744 52335)
 (symbols 48 37619 10)
 (strings 32 212084 10992)
 (string-bytes 1 7363735)
 (vectors 16 85260)
 (vector-slots 8 1762020 89727)
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 (buffers 992 52))

-- 
Matthias