Be able to mark self (VE) as Unavailable for one or more sessions
Be able to (ideally) select multiple sessions we have been added to as VEs and mark our selves as being unavailable to join them. This communicates to the Owner/Co-Owner our availability without interfering in whatever process they are using to set up sessions.
This would probably be nice then to have coupled with either a grouping or status icon for VEs inside the session list so the Owner/Co-Owner can see at a glance how many VEs are available or not.