I noticed the theme loaded when you hit "file->new" has a matching folder back arrow color, I was wondering how you got that since the option in settings doesn't seem to do anything. In my first theme I ended up just reworking an existing theme that had the correct arrow color.
Some notes for the two settings missing them:
Bottom solid
1. Upper empty slot shading
2. Main Color
3. Bottom empty slot shading
4. ???
Bottom outer
1. Horizontal stripes behind bottom buttons
2. Main Color
3. Shadowing near right and left edges
EDIT: Oh, bottom solid 4 is "shadow/glow around folder area" according to
this page. I suspected that much, but I couldn't isolate it by making everything else black/white. It should be the slight coloration around the entire center block in this case.