I'm 6'2, and I, like some others, try to be courteous by never reclining my seat all the way back, looking behind me to see who is sitting behind me, and putting my seat fully upright during meal service. (I'm the kind of guy who insists on getting to a movie theater early just to get a seat so whoever decides to sit behind me has a choice not to!), but on long haul daylight flights, it is annoying when the person in front of me decides to recline his/her seat back all the way when it really isn't necessary, but yes, I have figured out a way to strategically place my knees in a position where the person cannot recline. The person then gives up and things the seat simply doesn't work, then I go back and put my legs under the seat and stretch out, but always closely keeping alert if he/she tries it again. It works every time, and I know some might find it mean, but otherwise my legs would be spread in a manner as to impede on my neighbors space so I guess it's a trade off...