sproc(2) jobs updating the same window ?

[Marius Messerli]

I tried to creat multiple processes with sproc(2). These processes
should write into the same window to split the work to different 
cpu's. The job sharing works if I do something else (no gl operations) 
but fails to do anything upon gl-calls. 

sproc(entry, inh, arg);
with inh is set to PR_SALL

Thanks very much for any help!
Marius.