--- a/editors/Viewer.py	Mon Oct 09 12:30:14 2017 +0300
+++ b/editors/Viewer.py	Mon Oct 09 16:04:39 2017 +0300
@@ -3480,7 +3480,7 @@
             return True
         return False
 
-    def GenerateNewName(self, element=None, blocktype=None, exclude={}):
+    def GenerateNewName(self, element=None, blocktype=None, exclude=None):
         if element is not None and isinstance(element, SFC_Step):
             format = "Step%d"
         else: