[vtkusers] get sphere coordinates after moving

[Jazz Kartell]

hello everybody,

i have multiple sphere actors based on the coodinates from a vtkpoints 
object.
actually i can move a single sphere around (middle mouse button), but 
can't access the new coordinates.
i tried some examples dealing with coordinates, but it seems that these 
coordinates are not the ones used to place the spheres at the beginning...

So i need some kind of mapping between the sphere-actors and the 
underlying points in vtkpoints.
Finally, I want to update the coordinates in the vtkpoints after a 
movement...
Is that possible?

Best Regards

Benjamin