my workflow is probably a bit weird (because instead of asking this I could just try tweaking the HSV or color definition sliders), but I sometimes correct the overall color appearance of groups with the "enhance" live effect, eventually leading me to later pick those colors with the color picker

and i wonder if it would make any sense to let xara provide the color "enhance" dialog not only as live fx for every bitmap pixel, but also for the shape and line colors that exist in a group. this would make me better at choosing colors i believe