Subject: 28.0.50; Error running timer ‘custom-magic-reset’

From: David Ponce <[email-masked]>
Date: Thu, 23 Apr 2020 07:10:35 +0200

Hello,

Here is the recipe for an error I encounter when using customize with
2 windows in the same frame:

emacs -Q
M-x pop-to-buffer RET *Message*
M-x customize-variable RET blink-cursor-alist

At this point the *scratch* buffer is on top window and the customize
buffer on bottom.

Click on 'INS' button and insert a new Key/Value pair
Clict on 'State' button, then 'Set for Current Session'

Then click somewhere in the *scratch* buffer, then click on the 'DEL'
button in the customize buffer to delete the value previously entered.

At this point custom try to redraw the 'State' button in the *scratch*
buffer instead of the customize buffer! In this case, because the
*scratch* buffer is shorter than the position of the State button, it
fails with the error:

Error running timer ‘custom-magic-reset’: (args-out-of-range #<buffer
*scratch*> #<marker (moves after insertion) at 287 in *Customize Option:
Blink Cursor Alist*> #<marker at 294 in *Customize Option: Blink Cursor
Alist*>)

This error can be severe because, if in place of the *scratch* buffer
you were editing a file big enough to include the position of the 'State'
button, the 'State' button is drawn in your file without you realizing it!
And if you ever realize it, this change cannot be undone!

Thanks!

In GNU Emacs 28.0.50 (build 32, x86_64-pc-linux-gnu, GTK+ Version 3.24.13, cairo version 1.16.0)
  of 2020-04-23 built
Repository revision: 7b15cc3ebb45e50ac5faf3bbc2a813afffdaa418
Repository branch: master
Windowing system distributor 'Fedora Project', version 11.0.12006000
System Description: Fedora 31 (KDE Plasma)

Recent messages:
Mark set
Creating customization items...
Creating customization items ...done
Creating customization setup...done
Mark set
Beginning of buffer
Mark set [2 times]
scroll-up-command: End of buffer

Configured using:
  'configure --prefix=/home/dponce --with-cairo
  PKG_CONFIG_PATH=/usr/local/lib/pkgconfig:/usr/lib/pkgconfig'

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

Important settings:
   value of $LC_TIME: fr_FR.utf8
   value of $LANG: fr_FR.UTF-8
   locale-coding-system: utf-8-unix

Major mode: Messages

Minor modes in effect:
   tooltip-mode: t
   global-eldoc-mode: t
   electric-indent-mode: t
   mouse-wheel-mode: t
   tool-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
   auto-composition-mode: t
   auto-encryption-mode: t
   auto-compression-mode: t
   buffer-read-only: t
   line-number-mode: t
   transient-mark-mode: t

Load-path shadows:
None found.

Features:
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Memory information:
((conses 16 98994 16077)
  (symbols 48 10003 1)
  (strings 32 26548 2003)
  (string-bytes 1 811951)
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