This is a silly issue.
I'd be willing to testify in court that that implementation was clean. If such an issue were to ever come up, shoot me an email and I'll be there. Until then, you're going to have to take my word for it. And honestly, we do that with every bit of code we use every day. Do we really have anything except the author's word that he hasn't copied some GPL code?
And, if it ever does come up and a real clean-room implementation (with someone who's never seen FXT nor this thread) needs to be done, let me know about that, too. I know lots of kids who'd jump at the chance for a practice interview question.
I'll even do that now if Johan wants, but I doubt it's that useful. There are bigger fish in the sea, and you're chasing a minnow.
Regards,
- Clark