I know that spectral capability is coming to the color calibration at some point but this does not relate to that. What this was inspired from is this:
It would be really nice to have this in other modules as well in a way that does not populate the preset list. Here is a mockup:
By selecting a color circle is will automatically select the hue range that corresponds to that color.
I would be happy to work on this during the summer if this is of interest to others and to the darktable devs @anon41087856
