Flying in an F aisle seat once, I opened my mini-laptop, entered my password, and
OMG!!! - - I discovered that I had something EXTREMELY naughty on the screen!
I'm sure that a few people sitting behind me got a glimpse of something they have likely never seen before!
Needless to say that, whenever I'm packing my mini-laptop for a trip, NOW, I always check what's on the screen before putting it in sleep mode if I'm gonna use it on a flight.
That said . . . with the free 1 hour of T-Mobile GoGo wifi, I rarely need the laptop on a plane now.