    style = vtkInteractorStyleTrackballCamera()
    iren.SetInteractorStyle(style)

    #
    # Unlike the previous scripts where we performed some operations and then
    # exited, here we leave an event loop running. The user can use the mouse
--
    style = vtkInteractorStyleTrackballCamera()
    iren.SetInteractorStyle(style)

    #
    # Here we use a vtkBoxWidget to transform the underlying coneActor (by
    # manipulating its transformation matrix). Many other types of widgets
