to get an idea which layer is broken hold something to the window, like a pen or whatever. from the point where it touches you can get an idea how far the cracked layer is away.
i've been in an incident where we would've been able to continue flying for days. breakfast at dawn, bright glowing point appears in the sliding window and start eating its way thru the window. flipped OFF the window heat instantly, glow ceases. while we're still wondering -BANG- window covered in cracks. not funny. figured out it was the outer pane. but since the manuals don't contain advise on melting, glowin windows we went straight into emg desc.
since the side sliding window is inches from my head i felt quite uneasy. started to relax around 10.000ft as we depressurized the can.
if u tell me a window in the cabin blows, it's still something i wouldn't like. but better in the cabin than next to my face.
and one more thing: MEL window heat:
u can fly some days without. it's fine in the books. but: a 737 usually does some 2-10 (?) cycles a day. temperature change grd-FL summer 90°K, winter maybe still 60°K.
talking stressed materials.