bug#57468: 29.0.50; Text cursor continues to blink when frame loses focus

[Eli Zaretskii <eliz@gnu.org>]

> From: Bob Rogers <rogers@rgrjr.com>
> Date: Wed, 31 Aug 2022 12:02:04 -0700
> CC: Eli Zaretskii <eliz@gnu.org>, 57468@debbugs.gnu.org
> 
>    From: Lars Ingebrigtsen <larsi@gnus.org>
>    Date: Wed, 31 Aug 2022 12:03:38 +0200
> 
>    Bob Rogers <rogers@rgrjr.com> writes:
> 
>    >    Then I brought up a pre-existing emacs instance running as root
>    > (which I had forgotten about) and found that its blinking cursor stays
>    > on persistently, and the focus in/out code above shows that it's getting
>    > neither event.
> 
>    How was the root Emacs started?  Could it be in a way that stops the
>    window manager from delivering events to it?
> 
> Just "emacs &" after "su" in a shell.  I should emphasize that I've seen
> nothing special about the root emacs; all instances save one switched
> between working and nonworking at long but unpredictable intervals.  And
> the other problematic instances were also spawned from shells, though
> some were from a Konsole shell, some were via ssh with tunneled X11, and
> some from an emacs shell window.

I guess the next step is to set a breakpoint in every place where we
call x_focus_changed, and see whether the X events are delivered to
Emacs in the "su" Emacs.  If the events aren't delivered, this is not
an Emacs problem.