23.0.50; S-SPC remapped to C-@ for no good reason, severely reducing usability

[Tim Van Holder]

Since yesterday morning's build, S-SPC seems to have been mapped to C-@
for no apparent reason; while C-SPC is a reasonable binding for
set-mark-command, S-SPC is not: it occurs very frequently when typing.
I now find myself having to frequently go back and re-add spaces to code
because they were eaten by S-SPC.

What's worse, I have no way of finding out where the mapping comes from.
C-h k S-SPC gives

  C-@ (translated from S-SPC) runs the command set-mark-command
    which is an interactive compiled Lisp function in `simple.el'.
  It is bound to C-SPC, address@hidden

but it doesn't say where the translation comes from, and C-h b does not
list S-SPC as a translation, and only lists C-SPC and C-@ as bindings
for set-mark-command.

The translation seems to occur in all buffers, so it's probably some
global thing.


In GNU Emacs 23.0.50.1 (i686-pc-linux-gnu, GTK+ Version 2.8.20)
 of 2007-11-29 on leeloo
Windowing system distributor `RealVNC Ltd', version 11.0.3370
configured using `configure  '--with-gtk' '--with-xpm' '--with-jpeg' 
'--with-gif' '--with-tiff' '--with-png' '--with-x' '--with-kerberos' 
'--with-kerberos5''

Important settings:
  value of $LC_ALL: nil
  value of $LC_COLLATE: nil
  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_US.UTF-8
  locale-coding-system: utf-8
  default-enable-multibyte-characters: t

Major mode: C/l

Minor modes in effect:
  whitespace-global-mode: t
  show-paren-mode: t
  pc-selection-mode: t
  display-time-mode: t
  delete-selection-mode: t
  tooltip-mode: t
  tool-bar-mode: t
  mouse-wheel-mode: t
  menu-bar-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  font-lock-mode: t
  blink-cursor-mode: t
  unify-8859-on-encoding-mode: t
  utf-translate-cjk-mode: t
  auto-compression-mode: t
  size-indication-mode: t
  column-number-mode: t
  line-number-mode: t
  transient-mark-mode: t
  abbrev-mode: t