Following up to myself:

More bad features:

Scroll wheel support in MacOS is a hack (done by simulating a mouse click
  in the scroll bar -- if you turn on proportional scroll bars, you also get
  the arrows at one end (which is fascist); the top of the scroll bar becomes
  the gray "page scroll" area and scrolling up with the wheel is much faster
  than scrolling down)
Control panel is inflexible (a mouse button can't simulate a modifier key
  alone, which the Oberon GUI requires; on the other hand, the "slow mouse"
  and "axis" features can't be activated by mouse buttons but only by
  modifier keys)
Control key still brings up contextual menus even with a multibutton
  mouse (this is entirely Apple's fault; I just wanted to rant; they've
  had a multibutton mouse protocol for years; Jobs supposedly admitted
  that having a one-button mouse was wrong; they bought NeXT which at least
  supports two buttons; they were wise to "borrow" the idea of contextual
  menus from Windows; but they still couldn't bite the bullet and support
  more than one mouse button in the OS or probably the library functions)

The jury's still out on NetBSD support.

-- Derek