The problem here is that in real life, green glass is not '100% transparent', it is actually '0% R, 100% G, 0% B transparent'... ie if you shine a white light through it, it is transparent only to the green component and opaque to the rest, giving you green light. To duplicate this in CG, many render engines use a color value for transparency which they use in a similar fashion to color lighting effects, shadows etc and also correctly duplicate the effect you are talking about. Poser however treats it as a monochrome value so it wont have the same sort of result.... Maybe one of the tech guys can suggest an alternate solution.

Yet another reason to use other apps for rendering.