> A dedicated menu button on mouse is hard to discover. For what it's worth, it really wasn't. The meaning of at least the left and menu buttons was literally

> A dedicated menu button on mouse is hard to discover. For what it's worth, it really wasn't. The meaning of at least the left and menu buttons was literally the first thing you would find out when being shown how to use the machine, and was on the intro sheet in the (extensive and excellent) printed guides. The difficult-to-discover part was the right button ('adjust'), defined as doing whatever the left button did but a bit differently. So the left button might select a file, while the right button might add a file to the existing selection. Or a left click on the scroll bar 'down' arrow scrolls down, while a right click scrolls up (which was actually quite useful in pre-scroll wheel days as it saved a lot of precision mouse movements when searching documents etc.) This is really analogous to the discoverability problems that guis have with modifier keys - the right button is basically a sort of ctrl-click without needing to put your hands on the keyboard. But the menu button was just how you used menus. It was available and worked the same in essentially all applications and was really pleasant to use.