How revert folder tree "+" point from dark to light?

[pstein]

I must have accidentally changed the crossing points in folder tree on the left from light to dark backgrournd.

See attached snapshot

How can I switch it back to light?

[admin]

Ctrl+Right-Click one of those things and select what you prefer from the popup menu.

Well, you probably turned on the Mini Tree: View | Mini Tree | Mini Tree

[pstein]

Bingo!
That's it.
Thank you