{FMX} Can someone please help me with rotating a slider

Hello. I found a example of a slider.

here-> http://www.kirupa.com/developer/mx2004/menu_with_slider.htm

It’s working great. I have still much to learn but the examples are verry good.
But i would like the slider to rotate on a specified point. Is this possible with similar configurations of the file I found? I tried. And I can rotate the slider (in my case a round picture) but it wont stay on the same place.

gr, David (Netherlands)