# vtkSliderWidget doesn't display in my render window python

**URL:** https://discourse.vtk.org/t/vtksliderwidget-doesnt-display-in-my-render-window-python/2186
**Category:** Support
**Created:** [November 30, 2019, 2:24pm UTC](https://discourse.vtk.org/t/vtksliderwidget-doesnt-display-in-my-render-window-python/2186 "2019-11-30T14:24:03Z")
**Posts on this page:** 1
**Page:** 1

<div class="post-metadata">

### Author: ![kimia.af1998](https://discourse.vtk.org/letter_avatar_proxy/v4/letter/k/7ab992/32.png) [@kimia.af1998](https://discourse.vtk.org/u/kimia.af1998)
#### Post date: [November 30, 2019, 2:24pm UTC](https://discourse.vtk.org/t/vtksliderwidget-doesnt-display-in-my-render-window-python/2186/1 "2019-11-30T14:24:04Z")

</div>

Hi  
I have four QVTKRenderWindowInteractor and wants to add a slider into 3 of them.  
These sliders help to slide through slices.  
I cannot insert the slider into my render windows.  
I get this Error :

 ![Screenshot%20from%202019-11-30%2017-42-54](https://discourse.vtk.org/uploads/default/original/2X/6/68bb3984159ce63b9dbb7096430864ab59c4dc8c.png)  
and Here is my code :

```
    render_win=QVTKRenderWindowInteractor()
    interactor = render_win.GetRenderWindow().GetInteractor()

    self.sliderRep = vtk.vtkSliderRepresentation3D()
    self.sliderRep.SetMinimumValue(0)
    self.sliderRep.SetMaximumValue(self.slices_number)
    self.sliderRep.SetValue(0)

    self.sliderRep.GetPoint1Coordinate().SetCoordinateSystemToNormalizedDisplay()
    self.sliderRep.GetPoint1Coordinate().SetValue(0.9, 0.1)
    self.sliderRep.GetPoint2Coordinate().SetCoordinateSystemToNormalizedDisplay()
    self.sliderRep.GetPoint2Coordinate().SetValue(0.9, 0.9)
    self.sliderRep.SetSliderLength(0.075)  
    self.sliderRep.SetSliderWidth(0.05)
    self.sliderRep.SetEndCapLength(0.05)  
    self.sliderRep.BuildRepresentation()

    sliderWidget = vtk.vtkSliderWidget()
    sliderWidget.SetInteractor(interactor)
    sliderWidget.SetRepresentation(self.sliderRep)
    sliderWidget.SetAnimationModeToAnimate()
    sliderWidget.EnabledOn()
    sliderWidget.SetCurrentRenderer(widget.renderer)

    sliderWidget.AddObserver("InteractionEvent", partial(self.slider_update_call_back, vtkObj=self.sliderRep))
    render_win.GetRenderWindow().Render()
    interactor.Start()

```

and my UI is like this :

 ![Screenshot%20from%202019-11-30%2017-52-02](https://discourse.vtk.org/uploads/default/original/2X/0/0b3536b09509fc0dbd4c6342fa680c56a84c4262.jpeg)

Thank you for your helps.