We use a small amount of white foam type shaving cream. Place it on the glass, leaving it for a few minutes allowing it to dry. Then with a dry cotton cloth rub the glass until it shines. It serves multi-purposes. It will prevent the glass from fogging up, as would a mirror in a humid bathroom and it creates a protective glaze on the glass surface. The wax will certainly still fall, but you'll find, once it dries, it will eaasily 'fleck' off when you poke it with your fingernail.
I wish you the best of luck
Fr. Bill