This panel always open at the lowest possible level of my color variables structure.
I prefered the old behavior, where Sketch remembered my last choice for the document. Now when I switch:
… then close the panel and open it again, it’s back to the first screenshot.
I would like to work with my whole color palette, not to have to always keep going to parent or choose the parent folder.
Oh, and I also used to have folder titles:
So the titles are coming back!
Just to understand your library better to see how we can improve the first point. Your library only has 10 colours? Split by main and greyscale. Because you’re using main/red when you open, you see main, right?
I can understand in your case this is not what you want. This was something that was requested to us by people who use a large number of organised colour variables 
I’m not sure what the best ‘goldilocks’ solution is, but I will think about it.
Correct, exactly as you described. I like to keep my design systems lightweight.
If you’ve been requested this a lot, I can just put my colors into one group. Is there a way to order the colors, so that I don’t need to work around it with numerical prefixes?
