Add api to ibus for retreiving unused config values.

src/ibusconfigservice.h

Index: src/ibusconfigservice.h
diff --git a/src/ibusconfigservice.h b/src/ibusconfigservice.h
index cc446ecfa51be6a9e5bce4b8aa4eaabaf298dab9..48618ee8c4bd5734e647becd2f6290edc8994460 100644
--- a/src/ibusconfigservice.h
+++ b/src/ibusconfigservice.h
@@ -182,6 +182,10 @@ struct _IBusConfigServiceClass {
                                const gchar          *section,
                                const gchar          *name,
                                IBusError           **error);
+    gboolean    (* get_unused)(IBusConfigService    *config,
+                               GValue               *unread,
+                               GValue               *unwritten,
+                               IBusError           **error);
 
     /*< private >*/
     /* padding */
@@ -217,4 +221,3 @@ void                 ibus_config_service_value_changed
 
 G_END_DECLS
 #endif
-