While c3d13203 ensured that the test-client has actually closed the
window before testing for the focus change, it also made another timing
related issue with the tests more likely to happen. Serveral tests
assert that the focus is set to 'none' after the focussed window has
been closed when the window below does not accept focus. This however
can never be reliably tested, because closing the window triggers
timeout based iteration of a queue of default focus candidate windows.
This starts after the window has been closed and might finish before the
clients have finished synchronizing. This issue is more likely to
trigger the shorter the queue is and the more test clients there are
that could delay the synchronization.
https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1329
Some tests were not waiting for the test client to actually issue
destroy commands before checking their effect on the window focus.
Similarly when mutter is supposed to change the focus based on a delay
by sending a WM_TAKE_FOCUS to the client, this also could fail without
synchronization with the client before checking the result.
https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1325
As per commit f71151a5 we focus an input window if no take-focus-window accepts
it. This might lead to an infinite loop if there are various focusable but
non-input windows in the stack.
When the current focus window is unmanaging and we're trying to focus a
WM_TAKE_FOCUS window, we intent to give the focus to the first focusable input
window in the stack.
However, if an application (such as the Java ones) only uses non-input
WM_TAKE_FOCUS windows, are not requesting these ones to get the focus. This
might lead to a state where no window is focused, or a wrong one is.
So, instead of only focus the first eventually input window available, try to
request to all the take-focus windows that are in the stack between the
destroyed one and the first input one to acquire the input focus.
Use a queue to keep track of those windows, that is passed around stealing
ownership, while we protect for unmanaged queued windows.
Also, reduce the default timeout value, as the previous one might lead to an
excessive long wait.
Added metatests verifying these situations.
Closes: https://gitlab.gnome.org/GNOME/mutter/issues/660https://gitlab.gnome.org/GNOME/mutter/merge_requests/669
