UnacknowledgedEventCount > 0 is only partly useful as a session group selector
UnacknowledgedEventCount > 0 indeed creates a group, but if you want to read the messages before connecting you must go find the session in the other hierarchy, and the moment one clicks the messages button in the interface (6.x for sure), the messages for that session are marked read, and the session is dropped from the list, and because messages is now the flagged function this will repeat until the group is empty or one manages to click another section (hey it could happen if you have enough unacknowledged messages).
Obviously awesome response to have sessions that no longer meet the criteria dropped from most group (I use tbd.msi as my "go to" download that puts the client in "New Sessions" for Access, then I edit, obviously once I change CustomProperty1 it should and does disappear from that group and appear in the right group.
So perhaps this should be addressed in some other manner, but I have session group names that are a little "too long" such that I can't see the green dot after it, so the special group for unack was exciting at the first of the week, then I found the "catch".
currently there is a green dot on the group, but we have several hundred machines attached, would be nice to be able to have a group for those machines.