bug#67430: 29.1; <Multi_key> is undefined

[Eli Zaretskii]

> From: Po Lu <luangruo@yahoo.com>
> Cc: pot@gnu.org,  67430@debbugs.gnu.org
> Date: Sat, 25 Nov 2023 19:10:15 +0800
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> 
> > What other roles does this key play?  And how frequent is each role?
> 
> I don't know.  There is generally no other use for it under X, except
> perhaps as a modifier key, which if true Emacs won't register key
> presses at all.
> 
> > Also, if we bind this key by default as Francesco suggests, what
> > adverse results could this cause on the systems where this binding is
> > wrong?
> 
> Nothing beyond the obvious, to wit: Emacs will react to pressing the
> Multi_key as though it were bound to iso-transl-ctl-x-8-map.

Then maybe we should behave by default as Francesco suggested?  users
which don't like the results could always unbind/rebind the key.
WDYT?