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

[Eli Zaretskii <eliz@gnu.org>]

> From: Eshel Yaron <me@eshelyaron.com>
> Cc: aaronjensen@gmail.com,  monnier@iro.umontreal.ca,
>   trevor.m.murphy@gmail.com,  73862@debbugs.gnu.org
> Date: Sun, 08 Dec 2024 17:29:04 +0100
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> 
> >> From: Eshel Yaron <me@eshelyaron.com>
> >> Cc: Aaron Jensen <aaronjensen@gmail.com>,  monnier@iro.umontreal.ca,
> >>   trevor.m.murphy@gmail.com,  73862@debbugs.gnu.org
> >> Date: Sun, 08 Dec 2024 15:11:07 +0100
> >> 
> >> Eli Zaretskii <eliz@gnu.org> writes:
> >> 
> >> > We also haven't yet heard from Eshel.
> >> 
> >> I don't have any concrete suggestions at this point.  It's surely a
> >> complicated situation.
> >
> > Did you try the patch I posted, and if you did, did it resolve your
> > original problems?  
> 
> I did now, and it doesn't entirely solve the problem: with this patch,
> after remapping header-line in one buffer, the remapping now works for
> that buffer as expected, but it still also "spreads" to other buffers,
> which is unexpected.

What do you mean by "spreads to other buffers"?  When you remapped
header-line face before this change on master, did it behave
differently, and if so, how?