I think, it's the head movement in game. Move Forward, Backwards, left, right, and head tilt left and right, along with normal neck rotation. Please feel free to correct me if I'm wrong.
Edit: The F15 standalone is the same one as the one in flaming cliffs. And the clickable cockpits come with the titles labeled DCS: xxxx. Like the A10 or KA-50. The ones titled xxxx for DCS World do not have clickable cockpits (all the flaming cliffs aircraft)