Played a myriad of complex 4X games and I still can't work out how to trade basic agreements such as open borders and peace treaty. I can trade resources, but not agreements. From time to time the AI will offer an open border agreement, for example, but I still don't know how to initiate this myself. There's not selection option to trade open borders. Peace treaties are the same. Why is this sooooo difficult? What am I missing here?!