after an other Gem update, i found a problem
it concern most (all) primitive, and even other object (pix_video by example)
when this objets are create after the windows creation, they did not really work.
you have to destroy/create the Gem window in order to see a new primitive.
this cause major problem, i'll have to revert to an older gem version until it is fixed...
are you trying to implement multiple windows?
Cyrille