bug#73862: [PATCH] Add `header-line-active` and `header-line-inactive` faces.

[Eli Zaretskii]

> Cc: 73862@debbugs.gnu.org
> Date: Sun, 27 Oct 2024 12:46:53 +0200
> From: Eli Zaretskii <eliz@gnu.org>
> 
> > From: trevor.m.murphy@gmail.com
> > Date: Fri, 18 Oct 2024 05:56:32 -0700
> > 
> > Over the years I've put more and more information into the header line, and 
> > at some point I wanted to get that quick visual indicator of selected vs 
> > non-selected windows when I glanced at the header as I already got from the 
> > mode line.
> > 
> > This was surprisingly hard to achieve!  For a few years I used an ugly 
> > `buffer-list-update-hook` hack.  Then a few months ago I got adventurous 
> > and found that it actually wasn't as hard as I'd feared to hack these into 
> > the C source.
> > 
> > The new faces both inherit from the current `header-line` face, so there 
> > shouldn't be any visible impact if users don't customize the new faces.  
> > For cases like mine it's easy to customize header-line-inactive to inherit 
> > from mode-line-inactive.
> > 
> > Thanks in advance for your attention and feedback,
> 
> Thanks.  This changeset needs the appropriate changes in the Emacs
> user manual (which lists the standard faces in "Standard Faces"), and
> also a NEWS entry that announces the change.
> 
> Also, did you verify that modes which use header-line and customize
> the header-line face still work as before after this change, both when
> the window is selected and non-selected?

Ping! Trevor, could you please answer the above question, and provide
an updated patch with documentation changes?  I'd like to install this
as soon as these issues are resolved.