Folder tree "triangle" - change color?

Hello, I am customizing the colors of Directory Opus to have light text on a dark background. One thing I find annoying is that the little triangle thingie in the folder tree that indicates a folder has subfolders is apparently colored for only light backgrounds. Is there anyway to change the color of that little triangle so it shows up on a dark background? thanks for any info you can provide.

The glyphs come from the system-wide visual style that Windows uses.

You may find Preferences / Folder Tree / Appearance: Tree style = Lines works better with inverted colors.