bug#39687: 26.3; Add customize-variable option for not locking keyboards

[Eli Zaretskii <eliz@gnu.org>]

> From: Logan Perkins <logan@lp-programming.com>
> Date: Wed, 19 Feb 2020 21:01:30 -0800
> 
> Is there some further reason to lock the keyboard that I haven't
> considered?

Can we back up a little, and discuss the use cases where the current
behavior presents a limitation?  Is quitting in the other clients the
only one, or are there more?

Also, are you implicitly saying that several persons work
simultaneously vis-à-vis the same Emacs server?  Because if not, I'm
not sure I understand how simultaneous need to input from different
clients could even happen.

> Should I make the behavior depend on some elisp function? I think that
> might be the easiest way to support the "minibuffer in use" message and
> the like, but I'm not sure what the downside would be.
> 
> Is it a waste of time for me to submit patches related to this feature?
> If there's zero interest in adding this, or it would be less work for
> someone else to write it than review my patches, I won't waste your time
> sending them.

Speaking for myself, I think the interest depends on the relevant use
cases where the current behavior implies restrictions.  Thus my
questions above.

In any case, we thank you for your interest in Emacs and look forward
to seeing your contributions, but I suggest to start your legal
paperwork rolling now, because changes you are talking about will
probably be non-trivial in length, so we will need a copyright
assignment from you in order to accept the changes.  If you agree, I
can send you the form to fill and the instructions to go with it.