[jitter] fading between jit.gl objects that don't accept [matrixout 1]????

I am looking for a way to change one opengl scene to another but can't 
find a way of removing opengl content to make way for anything new. For 
example, I can easily xfade out old stuff with those gl objects that 
accept a [matrixout 1] message, but for those that don't, like 
jit.gl.gridshape or jit.gl.mesh, there doesn't seem to be a way.

Any ideas? Many thanks, Robbie.