For those of us who like to sit on window seat (or even anyone), do you guys like to keep the window open ?

I was looking at a video of how the new B787 will allow you to keep the window open (dynamic window tinting, ha), without letting light in disturbing other passengers.

So I was wondering, is there some 'rule' that windows should be closed at certain times? I for one like to keep the window open as I like to stare outside, but at the same time, if most everyone else has the windows closed (wanting to go to sleep?), I feel bad and feel compelled to close the window to be nice.

What are your thoughts?