As you can see in the shot, trying to put a path tile will hide the ice tiles underneath. I would except a transparent effect. Is this a missing feature or a bug?
Basically what is happening is intended. What you need to do is add an layer, put it above the snow (in z-pos, just put the snow on 0 and the path on 1), and make sure that the path is solid else tux won't interact with it. Hopefully this helped. (oh yeah also the layer thing is in objects)