Am I black-and-white yet?

[Henry Lieberman <lieber@MEDIA-LAB.MEDIA.MIT.EDU>]

On the issue of a reliable test for a black-and-white versus color screen,
I hit upon 

(real-color-equal (make-color 0 0 0)
                  (make-color 32000 32000 32000))

which asks "Is gray the same as black?". This seems to work.