Thanks Dave. I know that it tries, but IME with a dozen or so T-Birds, a hundred or so rental cars, and my own Sport Trac, that "feature" is very tricky to activate. You must keep the button depressed for long enough, or it will stop immediately as soon as you let go. If you stay on it for a tiny bit too long, it will go past the closed and locked position, and depending on which direction the window is moving, it will either go on to open up completely, or go to its "cracked open" position.
Some mechanisms work better than others, but none offer a reliable "go to closed and sealed" mode. Sometimes they overshoot a little, just enough that a hard rain can leak right through. The only way I've found to walk away from my car with reasonable certainty that It isn't going to leak is to watch and make sure that the guide pins drop into the part of the guides where the window is closed as far as it goes. And that's a pain.
I just went out to my ST to double-check its operation, and found that it does not stop at the closed position at all when going from "cracked open". The only way to get it to stop at "closed" is to open it up all the way, then move it back forward.
The moonroof is a four-figure option. With a price tag like that, I would be completely willing to pay an extra $25 or so that it would cost (including profit) to have a third button that positively closes and seals the moonroof window.