bug#2969: Emacs thinks the background-mode is "dark" on Windows, when registry key HKEY_CURRENT_USER\Control Panel\Colors is empty

[Michael Schierl <schierlm@gmx.de>]

Please describe exactly what actions triggered the bug
and the precise symptoms of the bug:


One one particular Windows system I have the effect that Emacs started
up with black text on white background, but the links were cyan (as if
the background was dark).

(frame-parameter nil 'background-mode) returned 'dark.

After a bit of investigation, I noticed that the registry key
HKEY_CURRENT_USER\Control Panel\Colors
did not have any values assigned. I don't know how this can happen, but
it seems that Windows copes very well with that, I never had any
incorrectly displayed program before.

The WINAPI call GetSysColor(5) still returns 0xFFFFFF, as expected, so
the background is drawn in white.

As a workaround, I changed one of the system colors in control panel, so
that Windows rewrote all the Colors keys in the registry. Now Emacs
looks fine. (This bug report text is from before the change, so you
still see the original error messages below).


In GNU Emacs 22.2.1 (i386-mingw-nt5.1.2600)
 of 2008-03-26 on RELEASE
Windowing system distributor `Microsoft Corp.', version 5.1.2600
configured using `configure --with-gcc (3.4)'

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: DEU
  locale-coding-system: cp1252
  default-enable-multibyte-characters: t

Major mode: Fundamental

Minor modes in effect:
  encoded-kbd-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
  blink-cursor-mode: t
  unify-8859-on-encoding-mode: t
  utf-translate-cjk-mode: t
  auto-compression-mode: t
  line-number-mode: t

Recent input:
M-x r e p o r t - e m <tab> <return>

Recent messages:
Unable to load color "SystemWindowText"
Unable to load color "SystemWindow"
Unable to load color "SystemWindowText"
Unable to load color "SystemWindow" [2 times]
Unable to load color "SystemWindowText"
Unable to load color "SystemWindow"
Loading emacsbug...
Loading regexp-opt...done
Loading emacsbug...done
Unable to load color "SystemWindowText"