window-x11: Focus the default window with delay while waiting for take-focus

When requesting to a take-focus window to acquire the input, the client may or
may not respond with a SetInputFocus (this doesn't happen for no-input gtk
windows in fact [to be fixed there too]), in such case we were unsetting the
focus while waiting the reply.

In case the client won't respond, we wait for a small delay (set to 250 ms) for
the take-focus window to grab the input focus before setting it to the default
window.

Added a test for this behavior and for the case in which a window takes the
focus meanwhile we're waiting to focus the default window.

https://gitlab.gnome.org/GNOME/mutter/merge_requests/307

src/tests/meson.build

@@ -114,6 +114,7 @@ stacking_tests = [
   'closed-transient-no-input-no-take-focus-parent',
   'closed-transient-no-input-no-take-focus-parents',
   'closed-transient-no-input-parent',
+  'closed-transient-no-input-parent-delayed-focus-default-cancelled',
   'minimized',
   'mixed-windows',
   'set-parent',

src/tests/stacking/closed-transient-no-input-parent-delayed-focus-default-cancelled.metatest

@@ -0,0 +1,36 @@
+new_client 2 x11
+create 2/1
+show 2/1
+
+new_client 1 x11
+create 1/1
+show 1/1
+
+create 1/2 csd
+set_parent 1/2 1
+accept_focus 1/2 false
+show 1/2
+
+create 1/3 csd
+set_parent 1/3 2
+show 1/3
+
+wait
+assert_focused 1/3
+assert_stacking 2/1 1/1 1/2 1/3
+
+destroy 1/3
+sleep 10
+
+assert_focused none
+assert_stacking 2/1 1/1 1/2
+
+activate 2/1
+wait
+
+assert_focused 2/1
+assert_stacking 1/1 1/2 2/1
+
+sleep 250
+assert_focused 2/1
+assert_stacking 1/1 1/2 2/1

src/tests/stacking/closed-transient-no-input-parent.metatest

@@ -1,3 +1,7 @@
+new_client 2 x11
+create 2/1
+show 2/1
+
 new_client 1 x11
 create 1/1
 show 1/1
@@ -12,9 +16,15 @@ set_parent 1/3 2
 show 1/3
 
 wait
-assert_stacking 1/1 1/2 1/3
+assert_focused 1/3
+assert_stacking 2/1 1/1 1/2 1/3
 
 destroy 1/3
+dispatch
 
-wait
-assert_stacking 1/1 1/2
+assert_focused none
+assert_stacking 2/1 1/1 1/2
+
+sleep 250
+assert_focused 1/1
+assert_stacking 2/1 1/1 1/2