[mutter] window: Allow grab if the display focus is unset

[Marco Trevisan <marcotrevi src gnome org>]

commit 84616bef27fb193cff901ca2a8b1ab65b6356c0e
Author: Marco Trevisan (Treviño) <mail 3v1n0 net>
Date:   Wed Jul 3 18:11:46 2019 +0200

    window: Allow grab if the display focus is unset
    
    As per commit 040de396b, we don't try to grab when shortcuts are inhibited,
    
    However, this uses the focus window assuming that it is always set, while this
    might not be the case in some scenarios (like when unsetting the focus before
    requesting take-focus-window to acquire the input).
    
    So allow the button grab even if the focus window is not set for the display
    
    Closes: https://gitlab.gnome.org/GNOME/mutter/issues/663
    https://gitlab.gnome.org/GNOME/mutter/merge_requests/668

 src/core/window.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/src/core/window.c b/src/core/window.c
index 185c92534..4c0761d70 100644
--- a/src/core/window.c
+++ b/src/core/window.c
@@ -8342,7 +8342,7 @@ meta_window_handle_ungrabbed_event (MetaWindow         *window,
   event_mods = clutter_event_get_state (event);
   unmodified = (event_mods & grab_mods) == 0;
   source = clutter_event_get_source_device (event);
-  is_window_button_grab_allowed =
+  is_window_button_grab_allowed = !display->focus_window ||
     !meta_window_shortcuts_inhibited (display->focus_window, source);
   is_window_grab = (is_window_button_grab_allowed &&
                     ((event_mods & grab_mods) == grab_mods));