[mutter] wayland: Check serial on wp_tablet_pad_strip.set_feedback

[Carlos Garnacho <carlosg src gnome org>]

commit 406677e2a0879924d45de1536ac9be056a827181
Author: Carlos Garnacho <carlosg gnome org>
Date:   Wed Jun 29 18:10:43 2016 +0200

    wayland: Check serial on wp_tablet_pad_strip.set_feedback

 src/wayland/meta-wayland-tablet-pad-strip.c |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)
---
diff --git a/src/wayland/meta-wayland-tablet-pad-strip.c b/src/wayland/meta-wayland-tablet-pad-strip.c
index 09f1e17..c2d047b 100644
--- a/src/wayland/meta-wayland-tablet-pad-strip.c
+++ b/src/wayland/meta-wayland-tablet-pad-strip.c
@@ -79,7 +79,8 @@ tablet_pad_strip_set_feedback (struct wl_client   *client,
 {
   MetaWaylandTabletPadStrip *strip = wl_resource_get_user_data (resource);
 
-  /* FIXME: check serial */
+  if (strip->group->mode_switch_serial != serial)
+    return;
 
   strip->feedback = g_strdup (str);
 }