[gtk/wip/chergert/quartz4u] macos: synthesize motion like we do on 3.x

[Christian Hergert <chergert src gnome org>]

commit fbacda54bea5d34c12eaf5538a37357621778447
Author: Christian Hergert <chergert redhat com>
Date:   Thu May 7 17:02:53 2020 -0700

    macos: synthesize motion like we do on 3.x

 gdk/macos/gdkmacossurface.c | 8 ++++++++
 1 file changed, 8 insertions(+)
---
diff --git a/gdk/macos/gdkmacossurface.c b/gdk/macos/gdkmacossurface.c
index 870b9b2510..c805961e17 100644
--- a/gdk/macos/gdkmacossurface.c
+++ b/gdk/macos/gdkmacossurface.c
@@ -729,6 +729,14 @@ _gdk_macos_surface_set_is_key (GdkMacosSurface *self,
 
       event = gdk_focus_event_new (GDK_SURFACE (self), keyboard, NULL, is_key);
       _gdk_event_queue_append (GDK_DISPLAY (display), event);
+
+      /* We just became the active window.  Unlike X11, Mac OS X does
+       * not send us motion events while the window does not have focus
+       * ("is not key").  We send a dummy motion notify event now, so that
+       * everything in the window is set to correct state.
+       */
+      if (is_key)
+        _gdk_macos_display_synthesize_motion (display, self);
     }
 }