Sumarizing the problem:
- GTA DOES have native gamepad support, but:
- The Character movement is Mapped to axes 0 and 1
- The Camera movement is Mapped to axes 2 and 3
- And there is NO WAY TO CHANGE. They really messed up there
- On Mac, the xbox 360 controller L Trigger is the axis 2...
- The L Trigger all the way up makes GTA "think" that it should rotate the camera to the left...
Since the game have native gamepad support, this is a problem that happens no matter if you have Joystick Mapper or not.
The only thing a ordinary user can do is use another gamepad in this case is try another (non-xbox) gamepad for this game.