I still think Borlox's idea is the smallest footprint one.
Just sets a flag for the specific popup and that's it.
Weab's idea of listening for the PARTY_MEMBERS_CHANGED event
and only hiding the popup (if it's there) after the party invite has gone through is also simple and minimal impact. (a different but clunky implementation of the same idea:
"hide the popup once you're sure the group inv has actually been accepted"
was my OnUpdate + check for GetNumPartyMembers())
Weab's way is much better if you go that approach.
The rest are all valid solutions but at the moment it's academic exercise imho.
Do you find a problem with either? I don't, while I find all comments
about "messing with more than needed" or "relying on a specific event firing order", valid.
I think we can safely assume that PARTY_INVITE_REQUEST will always precede PARTY_MEMBERS_CHANGED