For the purposes of this description, when I refer to "exporting tracks", I mean exporting either the audio or the midi (as you can do with Track->Export Tracks), and when I refer to "rendering", I mean exporting something so that it's complete (e.g. when you click "play" on qtractor, it renders the project to whatever it's connected to).
The only way to render a track using Qtractor (AFAIK), is to use the guide mentioned here (link is shortened for the purposes of not making this post overly long): http://goo.gl/bTgtN.
This, for me, is a rather ugly way of doing it, as it requires a lot of hand-work (plus finding the correct moment to stop it). So my suggestion is: Why don't we make it automatic?
I realize that it is hard (if not impossible) to use the fast-forward (or whatever it's called) from JACK when rendering MIDI, so let's ignore fast-forwarding for now.
I also realize that qtractor may not be able to actually find where the end of the track is. Here is two ways I can think of for doing it (I think both should be included, and make them as options):
As it's rendering, the trackhead (or whatever the little red line that shows you your position in the track) could move, to show where the rendering is at, and the user can stop the rendering at any time using the stop button.