Circling the default colors makes the shade slider jump around

[mpost]

Not necessarily a bug but confusing to the user: Circling around the color picker wheel makes the shade slider jump to different shades, producing different colors. I would expect the colors wheel to be stable when moving around on it.

When using the default ColorAdapater, selecting red at abut 80 degrees and making a 360° turn you end up on different shade of red than before since the shade slider jumps around.

[MarieSchweiz]

Its because the BW shades are missing. I've got a fix in my head and talk with lars about it.