It’d be lovely to have an option to turn the hue and saturation sliders for HSL/HSV colors to full brightness at all times. When you’re working on different shades on the same hue value, it becomes difficult to see the original base color you’re deriving from. Graphics Gale did this fairly well as you can see both the individual components and the final final color:
Really just a tiny option but it’d make it a lot easier to work with if you’re working with the color model directly. Most of the time I’m calculating component values manually to have a more consistent distribution across the available color space (e.g. gradients and shading). Seeing the base colors clearly without adjustments in brightness would make it a lot easier to work this way.