Quassel IRC

Reproduction Steps:

1. Open two clients connected to the same core
2. Have the core connected to at least two channels
3. Have one client select one channel, and ensure the second client does not have that same channel selected.
4. The channel the first client has selected will never indicate unread messages to the second client.

As a user of quassel who connects to a single core from Home and Work, I will often leave Quassel-Client running from home, with the channel I last interacted with still selected. When I connect to the core at work, the channel my client is connected to at home will never "highlight" to indicate new activity, since the client at home will mark it as "read".