Cross addon communication can be done be registering handlers listening for the message types used, I suppose?
Code:
Because the channel is very limited, there is currently only a maximum of 31 different message types supported.
If you are interested in adding a new message type, please contact me via pm and I will reserve an ID.
It is also encouraged to reuse existing message types and expand on them instead of adding a new one that does the same thing, but slightly different.