multi, None and validation

tiramisu/setting.py

@@ -178,7 +178,7 @@ class Setting(object):
     def __init__(self, context):
         # properties attribute: the name of a property enables this property
         # key is None for global properties
-        self._properties = {None: set(('expire',))}
+        self._properties = {None: set(('expire', 'validator'))}
         # permissive properties
         self._permissives = {}
         # generic owner