Severity: wishlist

In a recent discussion on emacs-devel,[1]

Eli Zaretskii <eliz@gnu.org> wrote:

>> The obsolete options use a different face.  However, it's not obvious
>> that this is the meaning of that face.
>
> IMO, we shouldn't show obsolete options at all in a Custom buffer, for
> the same reason why we remove them from the manuals.

How about the attached patch?