After serious thinking Pete Zahut wrote :
I reckon if you squirt steam at a double-glazed panel it's gonna crack, my
missus reckons that it should be OK given that there's a specific
tool/instructions to do so. Who's right - cos I don't fancy paying for a new
window!

I would guess that the localised heat would set up stresses in the
glass and that it might well shatter. Glass doesn't always shatter
straight away. You can drop a glass, pick it up then have it shatter a
week latter untouched, in the cupboard.

--
Regards,
Harry (M1BYT) (L)
http://www.ukradioamateur.co.uk