In reply to mark k..

The GPL is important for three reasons in this case. First, because of WordPress itself, and, unless Headway is written with absolutely no WordPress functions, (which I doubt) it's a derivative work. Second, listing a theme as 100% GPL when you're including a library that isn't GPL at all, or at least compatible with it, is a blantant falsification. Third, 90% of users don't care about the GPL, but that's because, for the time being, they're not being restricted in what they can do with WordPress ans associated plugins, themes, and other products. If that ever becomes a problem, they'd care real quick. And it's our job as developers to protect the rights that the GPL grants users. The 1% is supposed to care about it and abide by it so the 99% can afford to not care about it.