[gtk/gtk-3-24] Restore switching keyWindow when changing windows.

[John Ralls <jralls src gnome org>]

commit 9a0e40b6dab0564e230ce18d6c3a9b455217f3a7
Author: John Ralls <jralls ceridwen us>
Date:   Mon Mar 11 14:28:20 2019 -0700

    Restore switching keyWindow when changing windows.
    
    Inadvertently removed when converting from gdkdevicemanager to gdkseat.

 gdk/quartz/gdkevents-quartz.c | 3 +++
 1 file changed, 3 insertions(+)
---
diff --git a/gdk/quartz/gdkevents-quartz.c b/gdk/quartz/gdkevents-quartz.c
index 74f59b1e01..9d3d5bad58 100644
--- a/gdk/quartz/gdkevents-quartz.c
+++ b/gdk/quartz/gdkevents-quartz.c
@@ -1540,6 +1540,9 @@ gdk_event_translate (GdkEvent *event,
 
           grab = _gdk_display_get_last_device_grab (_gdk_display,
                                                     gdk_seat_get_pointer (seat));
+          if (!grab)
+            [impl->toplevel makeKeyWindow];
+
         }
     }