VTK: how can I add a scrollbar to my project ?

Question

What's the easiest way to add a scrollbar to my VTK project ?

thanks

Update

def vtkSliderCallback2(obj, event):
    sliderRepres = obj.GetRepresentation()
    pos = sliderRepres.GetValue()
    contourFilter.SetValue(0, pos)

SliderRepres = vtk.vtkSliderRepresentation2D()
min = 0 #ImageViewer.GetSliceMin()
max = 256 #ImageViewer.GetSliceMax()
SliderRepres.SetMinimumValue(min)
SliderRepres.SetMaximumValue(max)
SliderRepres.SetValue((min + max) / 2)
SliderRepres.SetTitleText("Slice")
SliderRepres.GetPoint1Coordinate().SetCoordinateSystemToNormalizedDisplay()
SliderRepres.GetPoint1Coordinate().SetValue(0.2, 0.6)
SliderRepres.GetPoint2Coordinate().SetCoordinateSystemToNormalizedDisplay()
SliderRepres.GetPoint2Coordinate().SetValue(0.4, 0.6)

SliderRepres.SetSliderLength(0.02)
SliderRepres.SetSliderWidth(0.03)
SliderRepres.SetEndCapLength(0.01)
SliderRepres.SetEndCapWidth(0.03)
SliderRepres.SetTubeWidth(0.005)
SliderRepres.SetLabelFormat("%3.0lf")
SliderRepres.SetTitleHeight(0.02)
SliderRepres.SetLabelHeight(0.02)

SliderWidget = vtk.vtkSliderWidget()
SliderWidget.SetInteractor(iren)
SliderWidget.SetRepresentation(SliderRepres)
SliderWidget.KeyPressActivationOff()
SliderWidget.SetAnimationModeToAnimate()
SliderWidget.SetEnabled(True)
SliderWidget.AddObserver("InteractionEvent", vtkSliderCallback2)