On Wed, Aug 18 2021, martin rudalics wrote:

> 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...

-- 
           Peter