I ask this because the Steam release of D3 is just a straight up rerelease. Nothing has been done to fix certain problems... like alt-tabbing and getting an exception error, which you can't actually acknowledge and have to close the game from the task manager. Has anything actually been done to the game besides erasing options from the launcher menu?

I don't believe so, although I'm not 100% sure.

Hmm, I was under the impression that they did, considering some games that didn't work under newer operating systems and hardware suddenly did, even without DOSBox. I may be remembering incorrectly, though.

D3 works fine without dosbox as it was a Win98/xp game. I have the original CD and install it without any issues.

More specifically, they probably don't *have* the code. Descent 3's source code was never released and it's unlikely that GOG was given it. If they had, you'd likely see patches above and beyond what had been originally released and the Descent community (outside here) would be aware of its existence. No evidence of a thing is just that.