UPDATE November 25 well GM backed out of coverying this on warranty. To add to the fustration, the rear frame is cracked. This seams to be another problem and related to the water penetration. So the frame cracks, my window breaks but it's not a warranty issue.
I'm not an engineer but if water enters the craked frame (as it did, and it freezes like it did, why can't these forces shatter the glass? Grrrrrr.....