The heck you do! Some people like to look out the window. That is why they ask for window seats.

I saw this situation happen on an America West flight last year. One guy in a window seat wanted his window open. He wasn't watching the movie but he did closed it half way to try and be accommodating. It wasn't enough for this bozo in the seat in front of me because there was one little patch of glare still in the bottom corner of the monitor. The FA talked to the guy in the window again and he refused to close his window any farther so the FA told the other guy there was nothing more she could do.