A lot of mapmakers have a tendency to emulate gravitator entity by adding an invisible door with a height of 1 pixel.
This isn't a bad idea, at least until the pusher above the gravitator inhibits a player with bad frames from jumping up. Or until the pusher inhibits a player with good frames from walking across the gravitator normally (without gliding).
A few popular maps that have this problem: blue---fv | mrblake213-war | rawrnuthug-pwn
I'm neither asking for these to be unapproved nor asking for them to be modified. I'm just letting other mapmakers know to make sure the pushers push a player up when said player jumps, not when said player is standing on the gravitator.