I appreciate the input of the question of beeswax solvent and will put that
information to use next season, as in the meantime I broke down and bought
new plastic.  The perfect solution, except for cost!  I'm particularly
intrigued about the 409 and the tri-sodium phosphate, both of which I have on
hand.
 
My problems with glass have mostly revolved around breakage while attempting
to remove panels that have been propolized in the cabinet slots.  The plastic
has been far-less vulnerable, but the eventual visibility problem is of
concern.
 
Thanks again,
Kate
([log in to unmask])
 
*************************************************************
 
Kate,
 
I don't know if this would work, but I'll throw it out for consideration:  line
the inside of the "windows" with clear cellophane; when they get dirty, peel
off and replace.
 
my .02 worth,  Chris Windsor