[PyMOL] mixing ray_shadows states

[Nat Echols]

I'm trying to make a high-quality figure showing ligand binding in a 
cleft, incorporating sticks, electron density, and some combination of 
cartoon/surface/lines for the protein.  Ray-traced shadows make the 
perspective much clearer but also add visual "noise" - for instance, the 
electron density casts mesh-shaped shadows everywhere.  Is there a way to 
prevent specific objects from casting shadows?  I tried

set ray_shadows = 0, mesh1
but this doesn't seem to have any effect.  (This is with a very recent 
beta.)  Is it even possible in theory for the raytracer to support such an 
option?