I can't off-hand remember any application where I was able to drag around buttons or, really, interact with them in any way other than pushing the button. That said, I don't think the widgets look particularly button-like (e.g. only the selected tab widget as any depth, the other widgets are flat).
Yeah good point, I don't know any either; guess it's more the "detachedness" than the "buttonness" that's supposed to hint at that. As I said, I'd be interested in seeing data on whether or not they were successful.
