We currently send chat state 'gone' when the Telepathy channel is closed, and Empathy closes Text channels when their window is closed.
telepathy-spec currently says:
# It may not be explicitly sent
# It should be automatically sent when the channel is closed
The XEP says:
> Definition: User has effectively ended their participation in the chat session.
> Suggested trigger: User has not interacted with the chat session interface, system, or device for a relatively long period of time (e.g., 10 minutes).
which isn't very helpful either.
One possible resolution is:
* Remove the two quoted bullet points from the spec
* Make Gabble not send <gone/> on Close()
* If UIs want to send the 'gone' state, they can treat it like any other state