Third, if we discover problems in the design, a prototype can be changed more easily, for the same reasons it could be built faster. Second, if we have a design decision that is hard to resolve, we can build multiple prototypes embodying the different alternatives of the decision. We build prototypes for several reasons, all of which largely boil down to cost.įirst, prototypes are much faster to build than finished implementations, so we can evaluate them sooner and get early feedback about the good and bad points of a design. What else has changed in modern scrollbars? Prototyping You can still click on the track above or below the thumb in order to jump by whole pages. This functionality hasn’t been eliminated from the modern scrollbar instead, the modern scrollbar just drops the obvious affordance for it. Why is that? What mental model would lead you to call that button down? Is that consistent with the mental model of the scrollbar thumb?Īnother interesting difference between the Star scrollbar and modern scrollbars are the - and + buttons, which move by whole pages. But they’re labeled the opposite way - the top button has a down arrow on it. Even its arrow buttons do the same thing - e.g., pushing on the top button makes more of the page appear at the top of the window, just like the modern scrollbar.
The Xerox Star offered the earliest incarnation of a graphical user interface, and its scrollbar already had many of the features we recognize in modern scrollbars, such as a track containing a scrollbar thumb (the handle that you can drag up and down). Scrollbars have evolved considerably over the history of graphical user interfaces.