bug#37774: 27.0.50; new :extend attribute broke visuals of all themes and other packages

[Eli Zaretskii]

> From: Andrey Orst <andreyorst@gmail.com>
> Date: Thu, 17 Oct 2019 17:13:00 +0300
> Cc: 37774@debbugs.gnu.org
> 
> > So maybe a few more faces need to be extended, at least optionally.
> > The issue that was brought up here was, AFAIU, that this feature
> > breaks many features so badly that it needs to be reverted or at least
> > turned off by default.  I have yet to see some sound arguments for
> > that.
> 
> Perhaps we need to see what developers of packages think about this change?

Everybody who has an opinion and arguments to back that up is invited
to speak up here.  TIA.