I've seen it mentioned somewhere, probably here on HN, that the original thin scrollbar was implemented in Gnome, and that it only applied until you moved your

I've seen it mentioned somewhere, probably here on HN, that the original thin scrollbar was implemented in Gnome, and that it only applied until you moved your cursor to it. If true, this sounds like a great innovation. Unfortunately, nobody bothers to expand the scrollbar when you get near it. And of course, scrollbars also didn't start to disappear until long after the square-ish monitors that made them so annoying were mostly replaced by widescreen monitors that didn't have that issue. Anecdotally, I do recall using an extremely obnoxious viewer application (PDFs or ebooks or some such) on the Windows 8 store that reversed scroll entirely. The scrollbars were still there (though I can't remember if they had handles), but scrolling the mouse wheel down moved the document up. The best UI is no UI--the program anticipates what you need and does it when you need it. Unfortunately, this is impossible in practice for anything other than the simplest systems (eg. pause music playback when the phone rings).