Dear all,
after the discussion of last SeeVogh meeting, and after several tests, I realized the better solution to avoid the stops in the geane propagation for long distances and to create a new release in a very short time is to modify the Geane.C, proposing larger epsilon for the "dangerous" materials:
TGeoMedium *m=gGeoManager->GetMedium("air");
m->SetParam(6, 0.005); // epsil
TGeoMedium *m2=gGeoManager->GetMedium("FscScint");
m2->SetParam(6, 0.005); // epsil
TGeoMedium *m3=gGeoManager->GetMedium("lead");
m3->SetParam(6, 0.005); // epsil
This modification is in the trunk since yesterday evening.