bug#43926: 26.3; Face `header-line-highlight': inherit from `mode-line-highlight', not `highlight'

[Drew Adams <drew.adams@oracle.com>]

> > > You want to have this face display as both raised-button _and_
> > > highlighted in color?  Which other applications do something like
> > > that?
> >
> > Dunno.  Does it matter which other apps do that?
> 
> Yes, because I think what you suggest will look uglier than what we
> have now.  It will also be unexpected.
> 
> > > Where the 3D face is not available, we do inherit from 'highlight'.
> >
> > The real point of this particular bug is to have
> > header-line inherit from mode-line.  Whether they
> > should inherit from `highlight' is another matter
> > (secondary).
> 
> I responded only to the "secondary matter".

OK.

None of this is a bug report - there's no bug.
I only provided some suggestions.

I'm using those suggestions myself now (just
started).  My impression so far is that it's
helpful to have the effect of face `highlight'
(whatever effect that might be for a given user
or library) included for mode-line construct
mouseovers.

For one thing, it's consistent.  (I don't argue
for consistency as a big deal.  Just sayin'.)

If I were to now sacrifice one of the parts:
(1) boxing & raising or (2) usual `highlight',
I think I'd sacrifice #1.

IOW, mouseover highlighting that everywhere
shows the same highlighted background makes
sense to me, for me.  But that's a personal
opinion.