laptop and mice

[Richard Wolff rwolff@noao.edu]

I'm considering buying a laptop and would like, of course, to consider
running plan 9 on it.  But all the machines have one button (apple) or
two button (windoz) mice built in.  Are there any machines with three
button mice?  (and supported by plan 9 ?)  Probably not, so the real
question is what are folks doing to provide the extra mouse button?  I
know that one could buy an external mouse and carry that around as
well, but that's not very elegant given that most everything else one might
want is now built it to the basic machine.  Using the alt, or better, the new
windows key, as either a third mouse button or a button modifier seems
better, but...has anyone done this?  Other ideas?

Richard