W.r.t. the problem of glass breaking as a result of propopolis buildup,
I've found that buying a bit of an aerosol product called "Baker's
Joy" has worked to help make it easier to take the glass out.
 I've found if you hold the glass next to a straightedge, with just
enough of the glass edge which will have contact exposed that you can
lay down a pretty straight line of this oil/flour mixture.
 My experiments aren't scientifically controlled- I could just be getting
better at taking things out, but I've the feeling that it's working better
than Pam, which is just straight oil.
 Maybe other folks can give hints about that- evidently some folks use
glass just fine and have other tricks-
 for what it's worth- Phil Wood