bug#48408: BUGFIX: window-default-font-height: check for nil string

[Eli Zaretskii]

> Date: Wed, 19 May 2021 07:55:37 -0400
> From: Boruch Baum <boruch_baum@gmx.com>
> Cc: rudalics@gmx.at, 48408@debbugs.gnu.org
> 
> > It's a "feature": Emacs can read input only from one frame at a time.
> 
> Without that feature, the emacs 'server' functionality could be  useful
> for >1 physical 'seats' (in X11/Xorg terms) or >1 separate IP addresses
> by >1 individuals. There had been attempts in the past at some FOSS
> version of 'collaborative editing' (eg. gobby), and I thought emacs had
> that covered with its server/client option.

Collaborative editing is much more than just getting input from
several sources.

> I'm looking at the emacswiki now ... and as so often the case it seems
> very out-of-date.
> 
> I don't personally have any immediate or foreseeable need for
> collaborative editing, but is there a 'recommended' method?

Someone posted here about a year ago describing the effort to add
collaborative editing to Emacs, look it up in the archives.