The Mission Tracker can take up a good deal of screen space in the UI. It would be great if we could collapse it on an icon, similar to the chat window, or close it altogether with a key bound to open it up again. It could also pop open when a new objective has been added or an objective completed.
Most of the missions are pretty simple. I don't need a chunk of the interface taken up by information that I already know or only access once or twice per mission. And I don't need to know what all my other missions are when I am already in one.