Messages app showing unread number after deleted message. Can remove/reset?

[dmoz]

Just what the title says, I deleted a group message in Messages, but it's still showing the unread number from that thread (see screenshot) and I can't bring up the group message because I deleted it . Short of having someone text in that group again to make it reappear, anyone know how I can fully delete the thread, or clear the unread number?

 

[GrumpyTrucker]

I usually try a killall Dock in Terminal when this happens. Usually works.