bug#57113: 29.0.50; Confusing icon customization interface

[Eli Zaretskii]

> Cc: 57113@debbugs.gnu.org
> From: Lars Ingebrigtsen <larsi@gnus.org>
> Date: Fri, 12 Aug 2022 17:32:43 +0200
> 
> Po Lu <luangruo@yahoo.com> writes:
> 
> > The labels on the various fields should also be more informative than
> > "Repeat", "String" and "Plist"; those only tell you what the fields are,
> > and not what the fields do.
> 
> If your point is that Customize sucks for complex structures, you're
> totally correct.

I think we shouldn't offer complex structures as values of user
options to begin with.  It makes no sense to me to require users to
understand such structures to be able to customize the respective
features.  I think the user options we have whose values are such
complex structures are simply cases of lazy thinking: it is much
easier for a Lisp programmer to make a defcustom that accepts such
complex values than to try to factor them into several simpler ones.

We should flatly reject such user options when they are introduced.