frame-set-background-mode changes frame background for special-display frames

[Drew Adams]

I don't have a simple recipe starting from emacs -Q, but I think I can
explain enough to make this clear. This major bug has been around
since at least 2005-06-26. I believe that it was introduced after
2005-04. Because I saw it only when used with my own code and it was
difficult to track down, and I figured it might have been transient
(due to a temporarily bad build), and I figured that if not, someone
else might discover and explain it better, I just lived with it.

The symptom I notice is this: I have a set of frame parameters for
special-display frames, and other sets for frames dedicated to buffers
*Help* and *Completions* (using `special-display-buffer-names' with
explicit frame parameters). What happens is that the background colors
of these frames are not what they should be.

The culprit, it turns out, is `frame-set-background-mode', which is
called from `x-create-frame-with-faces', which is called from
`make-frame', which is called from `special-display-popup-frame' or
whatever.

As its last action, `frame-set-background-mode' iterates over all
faces (that are not locally modified), calling (face-spec-set face
(face-user-default-spec face) frame). The last face affected is face
`default'.  The final culprit is this code:

(set-face-attribute 'default <:background attribute for default face>)

The value of that :background attribute is the default background for
`default-frame-alist' - that is, for non-special frames. So, what
happens is that the `default' face for the new, special frame has its
background set to the default value of the default face for the
default-frame-alist.  Changing the background of face `default' is
tantamount to changing the background of the frame itself, so as soon
as this face-attribute change is made, displaying (frame-parameters
<the new frame>) shows that its background has been changed to the
default background for default-frame-alist.

Sorry for being so wordy. I think this boils down to the fact that
face `default' should not be treated in the same way as the other
faces in this regard. Whatever properties a user has assigned to the
`special-display-frame-alist' or whatever should be respected.

Hope you can understand this description and find the fix.


In GNU Emacs 22.0.50.1 (i386-mingw-nt5.1.2600)
 of 2006-03-20 on W2ONE
X server distributor `Microsoft Corp.', version 5.1.2600
configured using `configure --with-gcc (3.4) --cflags -Id:/g/include'

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

Major mode: Dired by name

Minor modes in effect:
  encoded-kbd-mode: t
  tooltip-mode: t
  auto-compression-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
  line-number-mode: t

Recent input:
<help-echo> <help-echo> <help-echo> <help-echo> <help-echo>
<help-echo> <help-echo> <help-echo> <menu-bar> <help-menu>
<report-emacs-bug>

Recent messages:
(C:\Emacs-22-2006-03-20\bin\emacs.exe -q --no-site-file --debug-init
C:\drews-lisp-20)
Loading encoded-kb...done
For information about the GNU Project and its goals, type C-h C-p.
Loading dired...
Loading regexp-opt...done
Loading dired...done
Loading emacsbug...done