# QVTKInteractor cannot control the event loop

**URL:** https://discourse.vtk.org/t/qvtkinteractor-cannot-control-the-event-loop/8152
**Category:** Support
**Created:** [March 28, 2022, 6:32am UTC](https://discourse.vtk.org/t/qvtkinteractor-cannot-control-the-event-loop/8152 "2022-03-28T06:32:06Z")
**Posts on this page:** 2
**Page:** 1

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### Author: ![aveek-brahmachari](https://discourse.vtk.org/user_avatar/discourse.vtk.org/aveek-brahmachari/32/4481_2.png) [@aveek-brahmachari](https://discourse.vtk.org/u/aveek-brahmachari)
#### Post date: [March 28, 2022, 6:32am UTC](https://discourse.vtk.org/t/qvtkinteractor-cannot-control-the-event-loop/8152/1 "2022-03-28T06:32:06Z")

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With a vtkGenericOpenGLRenderWindow, I am trying to use the interactor style vtkInteractorStyleTrackballCamera along with vtkCallbackCommand and added an observer to vtkDistanceWidget.

I see that the vtkCallbackCommand is not executed and I get the error message “QVTKInteractor cannot control the event loop”.

What might be wrong ?

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### Author: ![sayunala](https://discourse.vtk.org/user_avatar/discourse.vtk.org/sayunala/32/6903_2.png) [@sayunala](https://discourse.vtk.org/u/sayunala)
#### Post date: [April 17, 2023, 4:58am UTC](https://discourse.vtk.org/t/qvtkinteractor-cannot-control-the-event-loop/8152/2 "2023-04-17T04:58:03Z")

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I have also encountered this problem. Have you solved it