Re: Making `x-underline-at-descent-line' a face attribute

[Eli Zaretskii <eliz@gnu.org>]

> Cc: luangruo@yahoo.com, emacs-devel@gnu.org
> From: Jim Porter <jporterbugs@gmail.com>
> Date: Thu, 6 Jan 2022 12:49:59 -0800
> 
> It's interesting that you mention web browsers in particular, since 
> that's part of what got me to think about using :box to create 
> nicer-looking tab-bar tabs. In Firefox, the visuals are determined by 
> CSS, and Emacs's :box attribute bears a striking resemblance to CSS's 
> `border'. Having done some similar UI design in CSS, I'd likely 
> implement the visuals for tabs partly using CSS `border' in the same way 
> that I described using :box. (Of course, I'd use many other CSS features 
> to adjust the appearance until it looks good.)

It may look similar, but it isn't.  Face properties are not meant to
produce 3D visual appearances of buttons and button-like widgets, they
are meant to support text display.

> > Once again, the released-button style should be produced by actually
> > drawing a released button, like we do on the tool bar and the mode
> > line.  Playing color games with the :box attribute will produce an
> > unclean emulation of that, and I therefore object to doing that.  We
> > shouldn't implement such unclean visuals.
> 
> I don't have a strong opinion on this, so I don't mind if :color stays 
> the way it is. It's just the first example I could come up with that 
> someone might use the feature for.

See above: I simply think that face properties are inappropriate for
this job.  They could be used for prototyping, but not for the real
thing, because it will just look bad.