(This is my first posting as a new user to test my account - so might have mistakes, etc. ) "창문이 저렇게 휠 정도로" is an adverbial clause (not a complete sentence). It means "To the extent the window gets bent like that", "So hard as to bend the window like that", or "hard enough to bend the window like that". 창문 window 이 subject particle 저렇게 like that; in that way; that much 휠 bend 정도로 to the extent; as much as (정도: degree/extent, 로: particle for means, way, methods)

The sentence in korean doesn't make sense! You got to copy and paste the original one.