[vtkusers] vtkWorldPointPicker does not see vtkImagePlaneWidget (vtk-5.0)

[Boris Avdeev]

Hello,
After I moved to vtk-5.0, I cannot pick a point on vtkImagePlaneWidget
with vtkWorldPointPicker anymore. Method GetPickPosition() returns
(0,0,0) instead.
Here is a relevant code:
...
    picker = vtkWorldPointPicker()
    iact = vtkRenderWindowInteractor()
    iact.SetPicker(picker)
...
    def PickingFunction(obj, event):
        global renWin
        print obj.GetPicker().GetPickPosition()  #gives (0.0, 0.0, 0.0)

    iact.AddObserver("EndPickEvent", PickingFunction)
...

Any suggestions?

Thanks,
Boris