TB, I agree that Fredo was extremely angry, but I still can't picture him tip-toeing around Michael's bedroom. Even if you could imagine him angry enough to set up Michael in some way, I can't ever picture him putting Kay or the children in harm's way, which is what he would have done by opening those drapes.

I think that most of his anger, incidentally, is with Vito. He is angry at being passed over, which is anger at Vito. Although Michael and Tom embarrassed him at the Vegas meeting, his anger seems to be at Vito for not even considering him "don-worthy". Michael, although younger, became his father figure, and the anger got redirected. Also, Fredo adored his father (brought out more in the book than in the movie, although his reaction to Vito's shooting is unbelievably touching), so he probably couldn't be consciously angry at his father.