You just have to send the drawto message to your jit.gl.model object
as well. But switching the drawing destination for a bunch of
objects and a renderer on every frame may get quite slow.
It might help you to look at the render_node patch I made for dealing
with this and some other common Jitter issues. The patch is at
http://2uptech.com/archive . It implements a preview window using
render-to-texture and slabs.