The one-button mouse is beyond obsolete. Why Apple sticks to it I cannot possibly understand. It made perfect sense in 1981 when we brought out the Lisa, with an unproved interface targeted at busy executives. We wanted an interface that could be learned in 20 minutes, and you can't do that with a mouse festooned with buttons.
Now it is almost 20 years later. The GUI interface seems to have caught on, and people recognize the advantage of learning it, even if it does take longer than 20 minutes.
I've been using a two-button mouse on my Macs for a couple years now, and no one could pry them away from me. The Kensington two-button mouse allows me to use the second button for System 8's context-sensitive menus, and even lets you set a third code for both buttons pressed simultaneously.
This two-button mouse, when coupled with the four standard modifier keys pressed with the left hand, offers users a far more expressive device than does Windows.
In principle, I'm not against adding more buttons, but only if some clear definition exists for each, so the user can predict what might happen were one pressed.
