Okay, I've downloaded a couple of fluxbox themes, opened a root Thunar, extracted to /usr/share/themes/, changed permissions of the new folders to be accessible for my username, and read for others. Closed, restart fluxbox, nothing, reload config, nothing . .
I cannot view them in the Appearance gui, or the Styles . . . reboot didn't help, is there a main file I have to update ?
(from box-look.org - murina_black, tin_black, noir)