Thanks, it's working fine. but i don't understand about math in this matter, but its ok i will learn it.
I through together a quick example for you. You can easily restrict the x position of the slider by setting the drag and drop behavior to just use the horizontal axis and then defining a maximum distance from the center of the background. To get the slider object to stay on the curved paths Y position though, you need to do some math. You'll need to figure out the radius of the circle path you want to follow. Everything else should be provided.