On Sun, Mar 22, 2015 at 3:31 PM, kilon alios <kilon.alios@gmail.com> wrote:
Color white - (Color white alpha:1.0) = Color black.
again reasonable

No, it's not really reasonable ;)
(Color white alpha: 1.0) = Color white => true

I personally assume to get Color transparent when subtract two absolutely equal colors.
And by the way there is no way in pharo to detect that they could be not equal:

��(Color white alpha: 1.0) != Color white

Color white - (Color white alpha:1.0)
The same as
Color white - Color white��


Cheers,
Alex��