[solved] Using z pos in a move?

[YinYin]

I followed your way of doing it and kept the chase, I added the hit_j tag and now I get what I want, except I'd like more infos on how the
hit_j tag works, because when im on the top of the screen, the ball travels down, but the closer I get to the bottom, the sooner it stops
going downwards. I wonder if the balls is rebounding on the bottom of the screen or something.

hit_j: 49 is a bit like dvz: -1
and hit_j: 51 like dvz: 1

You can push your object to the very back with hit_j: 1 within the first frame and then let it move the other way.