bug#4381: 23.1.50; Cocoa Emacs: face background for 'region set in ns-win.el after .emacs

[Erik Charlebois]

I did a deep dive and figured out exactly what is going on.

The (set-face-background 'region "ns_selection_color") that gets run  
in ns-win.el adds an entry to face-new-frame-defaults for 'region with  
"ns_selection_color" in the background slot. This gets persisted to  
the temacs-generated image.

In startup.el after (command-line) (and therefore, after .emacs runs),  
there's a call to frame-notice-user-settings. Because the background- 
color has been changed, a call to face-set-after-frame-default is  
made. This is turn calls internal-merge-in-global-face. This function  
overrides local settings with the global ones in face-new-frame- 
defaults, which clobbers the face setting.

The reason using set-face-attribute in .emacs works and custom-set- 
faces doesn't is because set-face-attribute (with nil frame) sets the  
value in face-new-frame-defaults.

Those are the gory details. I'm not sure what the right fix is.

Erik Charlebois
erikcharlebois@gmail.com

On 2009-09-13, at 6:09 PM, Glenn Morris wrote:

> Erik Charlebois wrote:
>
> > The minimal .emacs that shows the problem (extracted by digging into
> > the color-themes package):
> >
> > (setq default-frame-alist '((background-color . "white")))
> > (custom-set-faces '(region ((t (:background "red")))))
> >
> > The face setting is not honoured (reverts to ns_selection_color).
> >
> > If I do...
> > (set-face-attribute 'region nil :background "red")
> > instead of custom-set-faces, it works fine (but color-theme uses
> > custom-set-faces).
>
> Your problem sounds like this one:
>
> http://emacsbugs.donarmstrong.com/cgi-bin/bugreport.cgi?bug=2868
>
> (which unfortunately split into many different bugs rather than being
> all in the same one)
>
> I think the underlying problem is that ns-win is doing a slightly odd
> thing by calling set-face-background, and it does not play well with
> customize. See also bug #3408.
>
> The solution may be to change ns-win to use a more customize-friendly
> method of changing the face, if it really needs to do that.