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

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Message #5 received at submit <at> emacsbugs.donarmstrong.com (full text, mbox):

From: Michael Schierl <schierlm <at> gmx.de>
To: bug-gnu-emacs <at> gnu.org
Subject: Emacs thinks the background-mode is "dark" on Windows, when registry
 key HKEY_CURRENT_USER\Control Panel\Colors is empty
Date: Sun, 12 Apr 2009 19:41:50 +0200

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"

Message #12 received at 2969-done <at> emacsbugs.donarmstrong.com (full text, mbox):

From: Jason Rumney <jasonr <at> gnu.org>
To: Michael Schierl <schierlm <at> gmx.de>, 2969-done <at> debbugs.gnu.org
Subject: Re: bug#2969: Emacs thinks the background-mode is "dark" on Windows,
 when registry key HKEY_CURRENT_USER\Control Panel\Colors is empty
Date: Tue, 14 Apr 2009 00:23:32 +0800

Michael Schierl wrote:
> 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.
>   

Thank you for the report.

Emacs does not use GetSysColor, as to do so would require hardcoding 
system color names rather than reading them from the registry as it does 
now. White is used as a fallback, because it is the default background 
color for w32 frames.

I have changed frame-set-background-mode to take this into account 
instead of falling through to the default of dark when non-existent 
colors are specified.

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