I just updated the Diplomacy mod with some of these things:
- The server remembers which alliances it's notified you of, so it won't show you the same popup when you close and re-open the game.
- Your alliances are put on the top of the dialog to make them easier to see
- The players list no longer shows players who not in the game.
- Your pending proposals are shown in the dialog now, so if you don't accept or decline right away you can later choose to accept or decline it without having to re-load the game.
- If two players already have an alliance and make a new alliance, the new one will overwrite their old one. This sort of allows cancelling an alliance, as you can make a long one and later make a new 1-turn pact. If both players agree to the new shorter one, it will overwrite the old one and then expire after 1 turn.