However to get functionality in the second button you will need to download enabling software from the Contour web site. For software Contour decided to use a customized version of USB Overdrive by Alessandro Levi Montalcini, instead of developing something in-house. The software is good, if a little clunky. Alessandro, the genius behind KeyQuencer , is known more for his programming acumen than interface design. You can program the second button for all sorts of actions, from auto-scrolling to triggering keyboard keys or combination of keys.
Software settings can also be application specific.
For example you could have the second button scroll in Netscape Navigator,double-click in the finder and do something completely different in a third application. The second button is placed to the rear of the main button and is a little awkward to reach, but not disablingly so. The Contour mouse was also designed with the mobile computer user in mind. In addition to its small size, it comes with a small plastic carrying case into which you put the mouse and wrap the cord. This keeps the cord safe from kinking which Contour says is a big no, no.