What kind of 3-button mice are supported for use with X and how do they work?
From Ken Nakata (kenn@eden.rutgers.edu): Anything which supports Apple Extended Mouse Protocol. However, I know of only Logitech MouseMan/TrackMan that do support the protocol. For some unknown reason, each manufacturer seems to have decided to reinvent their own wheel. With the standard Apple mouse and a keyboard, the middle and right buttons are emulated by pressing the option key and left and right arrow keys, respectively. Logitech mice do not emulate the middle button; they return each button’s status in separate bit. You should be able to use a 3-button mouse from Logitech, MouseSystems, or their compatibles on PC, too. At least that was my experience with NetBSD 0.8 with XFree86 (a long time ago). Note, however, that key stroke generation is simulated by the device driver for Mac OS on some mice. If that’s the case, you won’t be able to generate the option-arrow sequence under NetBSD/mac68k. Further information regarding about the Extended Mouse Protocol is available on Apple’s
