Artemis makes use of all three buttons of the mouse under X, but other windowing systems often have less than three buttons. To make life easier when running Artemis on those systems, pressing the alt or meta key and the first mouse button will give the same effect as pressing mouse button three (usually a pop-up menu). Pressing the control key and the first mouse will do the same thing as mouse button two. On Macintosh machines the Apple key will do the same as the control key.