A sidebar to the article “Face to face with Open Look,” published in Byte, issue 13/88, pp. 290.

Open Look was designed to work with a one-, two-, or three-button mouse. The interface provides for three mouse functions called Select, Adjust, and Menu. Select lets you select and drag objects and manipulate controls such as buttons. Adjust lets you adjust a selection (such as selecting more text). Menu lets you display and choose among pop-up menus.

On a one-button mouse, the unmodified button is Select, with modifier keys (such as Alt or Option) required for the Adjust and Menu functions. On a two-button mouse, you use the left button for Select, the right button for Menu, and the Select button plus the keyboard Shift key for Adjust. On a three-button mouse, the default assignments of the buttons are, from left to right, Select, Adjust, and Menu. Again, these are the default assignments; regardless of the type of mouse, you can change them if you want. For example, on a two-button mouse, you could assign Adjust to the unmodified right mouse button and require a modifier key for Menu.