What I think would be a very good improvement is to have the option to cancel any trades you make.
For example say you find an intresting deal and send a trade request the recources for this trade are now out of your storage until the other person responds to your request. But if this person is offline and will, say, be back in a day or something the recources you put in this trade are no longer at your disposal thus slowing your development. What I think would be an improvement is to have the ability to cancel the trade request if it takes to much time to get the responce from the other person.