bug#9729: 24.0.50; can't editing buffers while in another buffer i'm openning files

[Eli Zaretskii]

> From: Lars Ingebrigtsen <larsi@gnus.org>
> Date: Fri, 16 Jul 2021 16:36:24 +0200
> Cc: 9729@debbugs.gnu.org
> 
> > 1)run emacs --daemon
> > 2)open two emacsclient on two seprate terminals
> > 3)on first emacs: C-x C-f   (and I don't Enter any file address)
> > 4)go to second terminal running emacsclient 
> > 5)I can't edit that buffer while go back to the first terminal (that I 
> > entered C-x C-f)
> > and enter C-g
> 
> (I'm going through old bug reports that unfortunately got little response at
> the time.)
> 
> I can confirm that this problem is still present in Emacs 28.  But I
> vaguely recall there being some discussion about this recently -- has
> Emacs gotten a way around this issue now?  Anybody remember?

It's a basic limitation of our keyboard input: we can only read from a
single frame at a time.