bug#66394: 29.1; Make register-read-with-preview more useful

[Eli Zaretskii]

> From: Thierry Volpiatto <thievol@posteo.net>
> Cc: monnier@iro.umontreal.ca,  stefankangas@gmail.com,  dmitry@gutov.dev,
>   michael_heerdegen@web.de,  66394@debbugs.gnu.org
> Date: Wed, 20 Dec 2023 17:23:14 +0000
> 
> >   . I suggest to rename all the "*basic" symbols to "*traditional"
> >     instead (including such words in some doc strings)
> 
> Ok, done.  Have a look though to verify if docstring is correct.
> 
> >   . I think we need to update the NEWS entry, and in particular
> >     describe there the two different "styles" of entering the register
> >     names and the preview modes
> 
> I would prefer you do this, it will be better written.
> 
> > (I'm okay with doing these minor changes myself, once you install the
> > changes.)
> 
> Ok, now merged, Thanks.

Thanks, I have a question:

The doc string of register-use-preview says:

  This has no effect when the value of `register--read-with-preview-function'
  is `register-read-with-preview-traditional'.

However, customizing register-use-preview to the value 'traditional
has the exact effect of setting register--read-with-preview-function
to register-read-with-preview-traditional.  OTOH, when
register-use-preview is set to 'traditional, one can set it to a
different value, and then the behavior will change.  So I wonder what
that sentence is about and what I missed?  Is that perhaps a leftover
from previous versions, and should now be deleted?

I updated the documentation and NEWS.  I'd appreciate if you could
spare a few minutes to review the changes and point out any
inaccuracies or mistakes.