Index: /home/heikki/workspace/chandler/parcels/osaf/framework/blocks/BranchPoint.py
===================================================================
--- /home/heikki/workspace/chandler/parcels/osaf/framework/blocks/BranchPoint.py	(revision 14059)
+++ /home/heikki/workspace/chandler/parcels/osaf/framework/blocks/BranchPoint.py	(working copy)
@@ -57,7 +57,9 @@
     A widget block that gives its BranchPointBlock a chance to change
     the tree of blocks within it.
     """
-    def wxSynchronizeWidget(self, hints={}):
+    def wxSynchronizeWidget(self, hints=None):
+        if hints is None:
+            hints = {}
         blockItem = self.blockItem
         if blockItem.isShown:
             blockItem.installTreeOfBlocks(hints)