bug#49997: 27.2; idle-time reset when switching desktop-page

[Eli Zaretskii <eliz@gnu.org>]

> From: Peter Münster <pm@a16n.net>
> Cc: Lars Ingebrigtsen <larsi@gnus.org>,  Eli Zaretskii <eliz@gnu.org>,
>   49997@debbugs.gnu.org
> Date: Wed, 18 Aug 2021 11:16:57 +0200
> 
> > I can offer the attached trivial patch.  Peter, can you try it?
> 
> Thanks. Yes, it works as expected.
> 
> Now the question is: is this the right thing to do?
> 
> According to Eli
> (https://lists.gnu.org/archive/html/bug-gnu-emacs/2021-08/msg01016.html)
> it's not so clear.
> 
> But on the other side, focus-out events and mouse movements keep the
> "idleness" too. So I guess, that frame movements could fall in the same
> category...

FWIW, I think this is a slippery slope, let alone
backward-incompatible change.  If we want to go anywhere near this
method, I'd suggest to create a variable with a list of events ignored
for the idleness purposes, which users could customize according to
their preferences and usage patterns (and, it turns out, their WM).
That would at least let users some kind of fire escape, whereas
hard-coding arbitrary events that we happen not to like this week
doesn't.

Btw, idleness is not the only feature related to this gray area:
there's also while-no-input, input-pending-p, and throw-on-input, to
mention a few.  Should these be in sync?