Can't maximize window

I assigned "spread with thumb and 2 fingers" to "maximize window" and it doesn't seem to do anything. I've tried restarting my machine.

Also, what I really want is to make the window fill my screen without "full screen" mode. (I don't like using full screen because of it's funky behavior with app switching.) Even if the gesture mapping worked, the "maximize window" command just toggles between 2 window sizes (I never could understand this behavior).

Any help appreciated, thanks!