Here are the photos I promised:
1.) Showing the black paint chipping/wear on the lift gate window interior:
Image One
2.) View showing the rust-colored defroster tracks (Left Side, viewed when window open and standing behind vehicle):
Image Two
3.) View showing the rust-colored defroster tracks (Right Side, viewed when window open and standing behind vehicle):
Image Three
Any comments, based on the photos -- does your interior of your lift gate window look more or less the same? I still haven't had a chance to clean the interior of the lift gate window (slightly damp cloth, no detergents or anything) to see if that white stuff (Image One) is just hard water... it looks for all the world like the black paint flecking off, but like I said, haven't fiddled with it to see if it's something else yet.