I've got a pile of old mice, both 1- (Apple, of course), 2- and 3-button, serial, RS232 ADB, USB and PS2. I can't recall ever needing to use or using the middle button a 3-button mouse.
I did train myself early on to use the mouse left-handed or right-handed. When working with graphics, a mouse is a killer for RSD for me. I've got trackballs (CH Products) as well as a couple of Cirque Glidepoint pads and briefly toyed with getting a foot-operated mouse wheel-thing. None of the alternatives worked as well as a plain old mouse. --Chuck
