(CellPicking)difference of vtkInteractorStyleTrackballActor and vtkInteractorStyleTrackballCamera

[hisupersylar]

today i study the demo of cxx/picking/cellpicking.
default ,the demo use the Interactor Style of vtkInteractorStyleTrackballCamera,the demo is ok.
in the demo,when we move mouse,Actually it change the camera postion.
the demo can't move single actor.
then i see the class vtkInteractorStyleTrackballActor, it can move single actor.
so i rewrite the demo.
i change the MouseInteractorStyle's parent class from vtkInteractorStyleTrackballCamera to vtkInteractorStyleTrackballActor, then the running result is not right.
for example,we run the demo again,we move the plane ,then pick the plane ,then the highlight part is always at the original postion, not the postion of actor when after moveing actor.

so, how to fix the problem?