This must be a bug though. If you unfold hidden comments, you jumpt to the BOTTOM, where you just WERE, rather than the top. So you scroll up, with no scrollbar, frantically, because you don't know how far you have to go. Until you reach the top - and you drag down ONE MORE TIME, because you're scrolling frantically, so the whole thread reloads, and everything is folded again, and you're back where you started.