[mutter] window: Don't use button grab modifiers with inhibit shortcuts

[Carlos Garnacho <carlosg src gnome org>]

commit 040de396b2ac2ea36de91a1173e84e44421efff3
Author: Olivier Fourdan <ofourdan redhat com>
Date:   Mon Jun 24 18:11:22 2019 +0200

    window: Don't use button grab modifiers with inhibit shortcuts
    
    On Wayland, if a client issues a inhibit-shortcut request, the Wayland
    compositor will disable its own shortcuts.
    
    We should also disable the default handler for the button grab modifier
    so that button events with the window grab modifiers pressed are not
    caught by the compositor but are forwarded to the client surface.
    
    That also fixes the same issue with Xwayland applications issuing grabs,
    as those end up being emulated like shortcut inhibition.
    
    Closes: https://gitlab.gnome.org/GNOME/mutter/issues/642

 src/core/window.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)
---
diff --git a/src/core/window.c b/src/core/window.c
index 121478331..185c92534 100644
--- a/src/core/window.c
+++ b/src/core/window.c
@@ -8267,7 +8267,9 @@ meta_window_handle_ungrabbed_event (MetaWindow         *window,
   MetaDisplay *display = window->display;
   gboolean unmodified;
   gboolean is_window_grab;
+  gboolean is_window_button_grab_allowed;
   ClutterModifierType grab_mods, event_mods;
+  ClutterInputDevice *source;
   gfloat x, y;
   guint button;
 
@@ -8339,7 +8341,11 @@ meta_window_handle_ungrabbed_event (MetaWindow         *window,
   grab_mods = meta_display_get_window_grab_modifiers (display);
   event_mods = clutter_event_get_state (event);
   unmodified = (event_mods & grab_mods) == 0;
-  is_window_grab = (event_mods & grab_mods) == grab_mods;
+  source = clutter_event_get_source_device (event);
+  is_window_button_grab_allowed =
+    !meta_window_shortcuts_inhibited (display->focus_window, source);
+  is_window_grab = (is_window_button_grab_allowed &&
+                    ((event_mods & grab_mods) == grab_mods));
 
   clutter_event_get_coords (event, &x, &y);