But we don't know if it was Fredo who opened the drapes. I believe that FFC would have made it a point to let us know at some point if it was Fredo.

I just think that he was dumb and really did not think that there was going to be a hit attempt on Mike. He even confirms this in his telephone conversation with Ola. "You guys lied to me."

Fredo was just stupid.

Now if Mike had him killed because he felt that Fredo's STUPIDITY could be a threat to his life, then that's a different story. But after Fredo's outburst I believe that Michael took it as if Fredo INTENTIONALLY set him up and betrayed him knowing that an attempt was going to be made on his life and that is why he had Fredo killed.