I had the following option in one of my templates:
tal:content="structure python:context.propname.menu(additional=
['propname1', 'propname2'])"

I expected this to display both propname1 and propname2 in the menu. It 
only displayed propname2.

I found some errors in roundup/cgi/templating.py and fixed them. A revised 
1.5.0 templating.py is attached. The changes are to the section "if 
additional:" in the LinkHTMLProperty.menu() method.