Trade Idea

It would be nice if the items listed on the trade board had a boarder or some sort of mark to indicate the seller is currently online.

I am not at home but iirc when you open the trade window there is an option to filter online only

Yup.
Press right thumbstick to toggle "show online only"

But you must make the choice between starting the search and finalizing the search - if you change your mind after the results appear, you must begin a new search, and make the toggle before finalizing the search (which is annoying, but it what we have at the moment). The choice will persist between searches.