# File vtk/tk/vtkTkRenderWindowInteractor.rb, line 244
  def MouseWheelEvent(event, ctrl, shift)
    @Iren.SetEventInformationFlipY(event.x, event.y, ctrl,
                                   shift, 0.chr, 0, nil)
    if event.delta > 0
      @Iren.MouseWheelForwardEvent
    else
      @Iren.MouseWheelBackwardEvent
    end
  end