Currently, when you're setting up a trade route and you can't afford the trade, it is difficult for me to tell if the sell button is active or not.
This! A million times this!
One of the main things i came to this forum to mention.
The sell button should be GLEAMING when you can sell and very dull when you cannot. Right now when I see three Sell buttons and they are all the same, I have no idea whether they are all available or unavailable becuase its not clear.