Index: gtkmain.c
===================================================================
--- gtkmain.c	(revision 21579)
+++ gtkmain.c	(working copy)
@@ -822,7 +822,7 @@
  * @entries: a %NULL-terminated array of #GOptionEntry<!-- -->s
  *    describing the options of your program
  * @translation_domain: a translation domain to use for translating
- *    the <option>--help</option> output for the options in @entries
+ *    the <option>--help</option> output for the options in @entries and the @parameter_string
  *    with gettext(), or %NULL
  * @error: a return location for errors 
  *
@@ -861,7 +861,8 @@
   
   context = g_option_context_new (parameter_string);
   g_option_context_add_group (context, gtk_group);
-  
+  g_option_context_set_translation_domain (context, translation_domain);
+
   if (entries)
     g_option_context_add_main_entries (context, entries, translation_domain);
   retval = g_option_context_parse (context, argc, argv, error);
