How do I write indicators using Python and GTK3?

[Jo-Erlend Schinstad]

I asked this question on AskUbuntu as well, but since there's been no 
answers, I'm repeating it here. The question is identical and can be 
found here: 
http://askubuntu.com/questions/108035/writing-indicators-with-python-gir-and-gtk3

I'm writing an application that needs to use an indicator. I've done 
this in the past using PyGTK and GTK2, using as reference this document: 
https://wiki.ubuntu.com/DesktopExperienceTeam/ApplicationIndicators#Python_version

However, that only works with PyGTK and GTK2. Things have changed since 
then, and I need to find some good documentation, a tutorial or a good 
example to learn how it works. If no tutorial exists, then I can write 
one – when I learn how it works. :)

Also, one thing that the previously mentioned document doesn't describe 
at all, is how to add sub-menus to an indicator. I hope someone can shed 
some light on this, as well as how to integrate with category indicators 
if that's done using the same tool.

Thanks.


-- 
Jo-Erlend Schinstad