I read gfx::Color src and notice:

**
** Return `argb` as the hash code.
**
override Int hash() { return rgb }

return rgb but expected return argb.

**
** Return `argb` as the hash code.
**
override Bool equals(Obj? that)
{
  x := that as Color
  return x == null ? false : x.argb == argb
}

wrong slot fandoc

thanks - I pushed a fix