bug#60356: 30.0.50; individual frame loses keyboard focus, focus cannot be restored

[Eli Zaretskii <eliz@gnu.org>]

> From: Linus Heckemann <git@sphalerite.org>
> Cc: 60356@debbugs.gnu.org
> Date: Tue, 03 Jan 2023 14:11:32 +0100
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> 
> >> I'd be glad if anyone could point out ways to further debug this issue.
> >> I'm also in #emacs:matrix.org (@linus:schreibt.jetzt) in case
> >> fast-turnaround communication would be helpful :)
> >
> > If you attach a debugger to Emacs in that state, and type
> >
> >   (gdb) thread apply all bt
> >
> > what do you get?  Please post here everything that GDB prints when you
> > do that.
> 
> Thread 1 (Thread 0x7f923ad21000 (LWP 19849) "emacs"):
> #0  0x00007f923c305151 in pselect () from /nix/store/4nlgxhb09sdr51nc9hdm8az5b08vzkgx-glibc-2.35-163/lib/libc.so.6
> #1  0x0000000000626b92 in really_call_select ()
> #2  0x000000000062731f in thread_select ()
> #3  0x0000000000649a51 in xg_select ()
> #4  0x00000000006005d3 in wait_reading_process_output ()
> #5  0x0000000000435846 in sit_for ()
> #6  0x0000000000524532 in read_char ()
> #7  0x0000000000524b30 in read_key_sequence ()
> #8  0x00000000005268b1 in command_loop_1 ()
> #9  0x000000000059f98f in internal_condition_case ()
> #10 0x0000000000511d86 in command_loop_2 ()
> #11 0x000000000059f8f3 in internal_catch ()
> #12 0x0000000000511d19 in command_loop ()
> #13 0x00000000005165ba in recursive_edit_1 ()
> #14 0x0000000000516937 in Frecursive_edit ()
> #15 0x000000000042abda in main ()

This says Emacs is waiting for input.

So if you type and that has no effect, perhaps the problem really is
that some wrong/non-existent frame has input focus?