Is is useful when adjusting colors. PS gives options inside hue/saturation tool to adjust 6 color zones individually using slider with 4 control bars, 2 for zone and 2 for falloff: http://www.entheosweb.com/photoshop/images/autumn_colors/autumn2-2b.jpg Gimp can select zone but it's not possible to adjust zone itself: https://docs.gimp.org/en/gimp-tool-hue-saturation.html ...similar to ps 2.5 tool: https://en.wikipedia.org/wiki/File:PS_2.5_hue-saturation_tool.png
I added my vote to the wish reported by Alex, but because the feature about vote disapeared today, I'm +1 this topic with a comment. :-)