Hi Most (all ?) fluxbox styles use bsetbg or bsetroot, but this programs are provided by blackbox. So fluxbox comes up with a black root color :-) fbsetbg and bsetroot-fluxbox should be used instead, perl can be used in the spec file to change this.
I'll post a bug report when qa.mandrakesoft.com is ok ;-) -- Olivier Blin