Currently there are two ways of leaning. The classic "Q" and "E" leans, and now the "ctrl + 'awsd'" leans. I think the game would be much smoother if instead of pressing all these buttons, you can press ctrl and then move your mouse to lean. Not much of a computer guy so idk if this is feasible in ArmA but I know its been done in other games. http://www.youtube.com/watch?v=3qqUrjajTaw