Re: Faces applies to new frames

[Stefan Monnier <monnier@iro.umontreal.ca>]

>>> +     ;; The face specs may specify a different default font.  Save this
>>> +     ;; in the `font' frame parameter.
>>> +     (setq default-font (face-font 'default))
>>> +     (when default-font
>>> +       (set-frame-parameter frame 'font default-font))
>> 
>> But doesn't that mean that (make-frame '((font . "foo-bar"))) will
>> disregard the explicit request for "foo-bar"?

> True.  I think that in this case, x-create-frame-with-faces should take
> note that it is passed a `font' frame parameter, and tell
> face-set-after-frame-default to stick to that instead of imposing
> whatever the `default' face says.

And that's exactly the reason why I introduced `font-parameter'.
Basically, I think that frame parameters should generally take
precedence since they may really be set on a frame-by-frame basis.
We can try and distinguish parameters coming from default-frame-alist
from those coming from elsewhere (pop-up-frame-alist,
minibuffer-frame-alist, ...), but it seems a simpler solution is to not
try and distinguish between the provenance and simply blindly give
priority to frame parameters.

This implies that set-face-attribute should probably store global
settings elsewhere than on default-frame-alist.  It sounds like
face-new-frame-defaults would be a good place for that instead (th0o
this is only based on its name)

Here's my current understanding of the various places where we store
face info:

- face-new-frame-defaults, should be global and seems to only ever
  contain "unspecified".  I.e. pretty much unused.
- defface.  Can go from global to terminal-specific.
  Usually terminal-specific.
- Xresources.  Can go from terminal-specific to frame-specific.
  Usually terminal-specific.
- default-frame-alist and other frame parameters.  Can go from global to
  frame-specific.

Are there any more?
I've sorted them based on their locality, so if we follow the principle
that more-local should take precedence over more global settings, they
should be taken in this order.  And indeed, I believe it's the order in
which they're applied right now.

Based on the above, we then have to figure out how set-face-attribute
(when applied globally) should affect the above settings, depending on
the effect we're looking for.

Here's a suggestion:
1 - rule out frame-specific Xresources settings
2 - make face-new-frame-defaults terminal-local, so it's initialized at
    terminal-creation time by applying defface and Xresources settings.
3 - rule that "global" set-face-attribute settings only apply to future
    frames on the same terminals (i.e. they're not truly global any
    more), so it can work by modifying the terminal's
    face-new-frame-defaults and it will hence take precedence over
    customize (i.e. defface) and Xresources settings.

This will also have the advantage that the only face-initialization we
need to do at frame-creation time is to apply the few face-relevant
settings from the frame parameters.  I.e. It will speed up frame creation
significantly when you have many faces.


        Stefan