this should work in RoboFont 1.7

good luck

from mojo.events import addObserver

class test(object):
    
    def __init__(self):
        
        addObserver(self, "fontOverviewAdditionContextualMenuItems", "fontOverviewAdditionContextualMenuItems")
        
    
    def fontOverviewAdditionContextualMenuItems(self, notification):
        
        myMenuItems = [
            ("Hello", self.sayHello), 
            ("World", self.sayWorld),
            ("submenu", [("an item", self.sayAnItem)])
            ]
        
        notification["additionContextualMenuItems"].extend(myMenuItems)
    
    def sayHello(self, sender):
        print "Hello"
    
    def sayWorld(self, sender):
        print "World"
    
    def sayAnItem(self, sender):
        print "an item"

test()