Right just hear me out

IMO The shooters were about to kill mike by going in to the house, this explains why they needed Fredos information about the compound and where the corleone men were and how to get in to the house (assuming fredo was dumb enough to believe that Roth wanted to kidnap Mike and no harm would come to him). However as they are about to do it they see the drapes are open and try to kill mike but they mess it up.

Many people agree that Anthony opened the drapes to see where his father was (to see the pitcure). I also beieve that Kay probably got dressed in the bathroom and was too tired to see if the drapes were open (it was a long and tiring party)and went straight to bed, Then mike comes and then she realises the drapes are open.

Thats what i think. I'm not sure if anybody has came up with a conclusive answer to this or has said this before but thats my thought.

What do you think.