How to reproduce:
1: Invite someone to a party
2: Open interface options
3: Hit Esc

Oh, I remember seeing that. Thanks for reminding me :). I'll see if I can push a fix soonish.

Great :)

Also, since oUF unregister most of the events for the default party frames, these will still show, and not update, when party members change or if you leave the party.

That's really just a sub-issue of this. I unregister the events so it doesn't actually update.

Fixed with e8119c3.