>> I've also made some new changes in customize.texi after I sent this
>> patch. They are equivalent to those in the docstring of
>> `defcustom'.
>
> I didn't see any new version of the proposed patch in this bug report?

Sorry, I was waiting for more feedback in other parts of the patch
before sending it. I send a new version now with the typos you pointed
out fixed, and the changes in customize.texi that I said. I've also
dropped some of the changes in the previous path that I don't think that
were actually necessary, to keep the patch and review simpler.

--Ignacio