most of the buttons of the Kensington Expert Mouse Pro
aren't recognised by the usb mouse driver. I've checked
it with cat on the device. When I look into the driver,
it seems that it really doesn't know all buttons. For
your info, it has 4 normal buttons, 6 additions buttons
on the top, and a scrolling wheel which can be also
used as button.
WKR Torsten Knodt