I have Carrara 4.
I had an idea to experiment with makeing  a stained glass window. To start, I made a hollow cube placed on a plane and put my only sourse of light in the cube. I cut a square window in one wall of the cube and  placed a colored piece of glass in the hole. I render it and the window glows but does not cast light on the outside of the cube on the plain. How do you make that happen?
I had "Light through Trans" checked in the Render room.