I want to create an extension that addes a menu item to the context menu of a file. I want to give this menu a submenu, but the current API won't allow this. Here is a simple example that gave me this error

import pygtk
pygtk.require('2.0')
import gtk
import nautilus

class ExampleExtension(nautilus.MenuProvider):
	def __init__(self):
		return
		
	def get_file_items(self, window, file):
		item = nautilus.MenuItem('NautilusPython::example_file_item', 'Example', 'Example tip')
		item.set_submenu(gtk.Menu())		
		return item,


And the error returned is

    item.set_submenu(gtk.Menu())
AttributeError: 'nautilus.MenuItem' object has no attribute 'set_submenu'

This makes sense, as set_submenu must not be implemented in the nautilus package, however, I feel it should be provided and would be useful for my extension.