In relation to opening the 172's windows in flight. I flew one or two that had a warning label attached. It said 'Do not open window above 160 Knots'.. .As the VNE is 160 knots, opening the window would be the least of your worries at that point.. .. .In terms of opening doors. I must say it never occurred to me to try and steer with them. On a serious note more than one accident was caused by an overr eaction to an open door. Spinning in as you try to close a door really ruins your day.