# ScaleBar Observer

**URL:** https://discourse.vtk.org/t/scalebar-observer/13532
**Category:** Support
**Tags:** python
**Created:** [March 14, 2024, 8:06am UTC](https://discourse.vtk.org/t/scalebar-observer/13532 "2024-03-14T08:06:00Z")
**Posts on this page:** 1
**Page:** 1

<div class="post-metadata">

### Author: ![Mordrago](https://discourse.vtk.org/user_avatar/discourse.vtk.org/mordrago/32/8974_2.png) [@Mordrago](https://discourse.vtk.org/u/Mordrago)
#### Post date: [March 14, 2024, 8:06am UTC](https://discourse.vtk.org/t/scalebar-observer/13532/1 "2024-03-14T08:06:00Z")

</div>

Hello!  
I want to AddObserver onto scale bar, but i dont know how. I added doubleclick event to int, but it is not working:

```auto
self.scalar_bar = vtkScalarBarActor()
self.scalar_bar.AddObserver("LeftButtonDoubleClickEvent", self.scale_bar_settings_dialog)
self.ren.AddActor2D(self.scalar_bar)

```

```auto
def scale_bar_settings_dialog(self, obj: vtkObject, _event: int) -> None:
        """."""
        print("Test")

```

Idk, why. Can somebody give me a hint?