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

[Eli Zaretskii]

> From: Po Lu <luangruo@yahoo.com>
> Cc: emacs-devel@gnu.org
> Date: Thu, 06 Jan 2022 20:24:07 +0800
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> 
> > I'd prefer to enhance :underline.  Introducing a new attribute might
> > be more tricky, as our experience with :extend shows.
> 
> Could you elaborate on that? It could be knowledge that would come in
> handy for me in the future.

What would you like me to elaborate on? the :extend attribute? or
something else?

> > For example, we'd need to decide how to reconcile that new attribute
> > with :underline, for starters.
> 
> That would be fairly simple: :underline doesn't accept any attribute
> that changes the position of the underline, so I don't know why they
> would conflict.

For example, what does it mean when a face specifies this new
attribute, but doesn't specify :underline?  Or what if it does specify
:underline, but its style is 'wave'?