[gedit-plugins] Fixes an exception when invoking bookmarks pluggin for commander

[Jordi Mas <jmas src gnome org>]

commit 5860a75602489b0c633bacb8eb65e0981456e202
Author: Jordi Mas <jmas softcatala org>
Date:   Tue Jun 4 12:52:26 2019 +0200

    Fixes an exception when invoking bookmarks pluggin for commander

 plugins/bookmarks/messages/gedit-bookmarks-message-toggle.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/plugins/bookmarks/messages/gedit-bookmarks-message-toggle.c 
b/plugins/bookmarks/messages/gedit-bookmarks-message-toggle.c
index 96c2d5b..158f0ae 100644
--- a/plugins/bookmarks/messages/gedit-bookmarks-message-toggle.c
+++ b/plugins/bookmarks/messages/gedit-bookmarks-message-toggle.c
@@ -38,7 +38,7 @@ struct _GeditBookmarksMessageTogglePrivate
        GtkTextIter *iter;
 };
 
-G_DEFINE_TYPE (GeditBookmarksMessageToggle, gedit_bookmarks_message_toggle, GEDIT_TYPE_MESSAGE)
+G_DEFINE_TYPE_WITH_PRIVATE (GeditBookmarksMessageToggle, gedit_bookmarks_message_toggle, GEDIT_TYPE_MESSAGE)
 
 static void
 gedit_bookmarks_message_toggle_finalize (GObject *obj)