Add api to ibus for retreiving unused config values.

ibus/config.py

Index: ibus/config.py
diff --git a/ibus/config.py b/ibus/config.py
index d4d100e2dfaf567333979d337a49a09b5529e590..87ac8b7cb1816b20d68e7514a26aebdcf3230492 100644
--- a/ibus/config.py
+++ b/ibus/config.py
@@ -49,6 +49,9 @@ class ConfigBase(object.Object):
     def unset(self, section, name):
         pass
 
+    def get_unused(self, unread, unwritten):
+        pass
+
     def value_changed(self, section, name, value):
         self.__proxy.ValueChanged(section, name, value)
 
@@ -68,6 +71,9 @@ class ConfigProxy(interface.IConfig):
     def Unset(self, section, name):
         return self.__config.unset(section, name)
 
+    def GetUnused(self, unread, unwritten):
+        return self.__config.get_unused(unread, unwritten)
+
     def Destroy(self):
         self.__config.destroy()
 
@@ -144,6 +150,12 @@ class Config(object.Object):
         except:
             return
 
+    def get_unused(self, unread, unwritten):
+        try:
+            return self.__config.GetUnused(unread, unwritten)
+        except:
+            return
+
     def set_list(self, section, name, value, signature):
         return self.set_value(section, name, dbus.Array(value, signature=signature))