hi curaga,
thank you for your explanation.
now i understand and i can confirm that it's a kind of sequence problem,
the order of loading or the time gap between processes...
actually i didn't find a clean solution,
not with loading wbar in the ~/.fluxbox/startup,
not in my ~/.X.d/.startup or with the help of my .xsession.
so i stay in the moment with my stable, although quick & dirty, solution i mentioned above.
if you know clean solution, i appreciate every help.
thank you.