[gnome-photos] embed: Update comment about GTK+ workaround

[Debarshi Ray <debarshir src gnome org>]

commit 44bed2be16a2bf2d0d9aad8fd7a1c60a61555101
Author: Debarshi Ray <debarshir gnome org>
Date:   Wed Dec 30 11:50:28 2015 +0100

    embed: Update comment about GTK+ workaround
    
    ... by referring to the fix so that we don't forget to remove it once
    it is old enough.

 src/photos-embed.c |    4 +++-
 1 files changed, 3 insertions(+), 1 deletions(-)
---
diff --git a/src/photos-embed.c b/src/photos-embed.c
index 6e65f0b..1935415 100644
--- a/src/photos-embed.c
+++ b/src/photos-embed.c
@@ -647,10 +647,12 @@ photos_embed_dispose (GObject *object)
   g_clear_object (&priv->srch_cntrlr);
   g_clear_object (&priv->trk_ovrvw_cntrlr);
 
-  /* GdStack triggers notify::visible-child during dispose and this means that
+  /* GtkStack triggers notify::visible-child during dispose and this means that
    * we have to explicitly disconnect the signal handler before calling up to
    * the parent implementation, or photos_embed_notify_visible_child() will
    * get called while we're in a inconsistent state
+   *
+   * See https://bugzilla.gnome.org/show_bug.cgi?id=749012
    */
   if (priv->stack != NULL)
     {