Re: Emacs design and architecture. How about copy-on-write?

[Eli Zaretskii]

> From: Ihor Radchenko <yantar92@posteo.net>
> Cc: dmitry@gutov.dev, luangruo@yahoo.com, acm@muc.de, incal@dataswamp.org,
>  emacs-devel@gnu.org
> Date: Fri, 22 Sep 2023 13:06:00 +0000
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> 
> > You will need to describe in more detail what you mean by "user
> > interaction with a window".  In Emacs, users don't interact with
> > windows, they interact with Emacs.  Did you mean that such a window
> > should not be the selected one?
> 
> I meant that such a window can be selected, but attempting to do
> anything that interacts with the window should cause user-error while
> the window is being processed by redisplay.
> 
> I imagine that users will be allowed to, at least, C-x o away from the
> window or switch buffer. But not enter text or run arbitrary commands.

That is still far from complete.  But in any case, this seems to
require addition of tests to many Emacs primitives, which would check
if the selected window is "kosher", and if so, produce a user-error.