# RemoveAllObservers do not work
**URL:** https://discourse.vtk.org/t/removeallobservers-do-not-work/4796
**Category:** Support
**Created:** [December 9, 2020, 1:50pm UTC](https://discourse.vtk.org/t/removeallobservers-do-not-work/4796 "2020-12-09T13:50:38Z")
**Posts on this page:** 3
**Page:** 1
### Author:  [@zhang-qiang-github](https://discourse.vtk.org/u/zhang-qiang-github)
#### Post date: [December 9, 2020, 1:50pm UTC](https://discourse.vtk.org/t/removeallobservers-do-not-work/4796/1 "2020-12-09T13:50:38Z")
I want to remove all observers in interactor, but it do not work. My code is:
```auto
from PyQt5.QtWidgets import *
import sys, os
import vtk
from vtk.qt.QVTKRenderWindowInteractor import QVTKRenderWindowInteractor
def mouseMoveEvent(iren, event):
print('move')
class MyWin(QWidget):
def __init__ (self):
super(). __init__ ()
layout = QVBoxLayout()
self.setLayout(layout)
self.vtkWidget = QVTKRenderWindowInteractor()
layout.addWidget(self.vtkWidget)
self.ren = vtk.vtkRenderer()
self.vtkWidget.GetRenderWindow().AddRenderer(self.ren)
interactor = self.vtkWidget.GetRenderWindow().GetInteractor()
interactor.Initialize()
interactor.RemoveAllObservers()
interactor.AddObserver('MouseMoveEvent', mouseMoveEvent)
interactor.Start()
self.imageViewer = vtk.vtkImageViewer2()
self.imageViewer.SetupInteractor(interactor)
self.imageViewer.SetRenderWindow(self.vtkWidget.GetRenderWindow())
img = vtk.vtkDICOMImageReader()
img.SetFileName('C:\\Users\\MLoong\\Desktop\\dicom_data\\Chang Cheng\\TOF\\IM_0174')
img.Update()
self.imageViewer.SetInputData(img.GetOutput())
self.imageViewer.Render()
if __name__ == ' __main__':
app = QApplication(sys.argv)
window = MyWin()
window.show()
app.exec_()
```
Is there anything wrong with my code?
---
### Author:  [@Joachim\_P](https://discourse.vtk.org/u/Joachim_P)
#### Post date: [December 11, 2020, 4:18am UTC](https://discourse.vtk.org/t/removeallobservers-do-not-work/4796/2 "2020-12-11T04:18:43Z")
Hi,
Could you please be more specific and explain what do you get, what do you expect and what you think is not working here?
J.
---
### Author:  [@zhang-qiang-github](https://discourse.vtk.org/u/zhang-qiang-github)
#### Post date: [December 11, 2020, 12:03pm UTC](https://discourse.vtk.org/t/removeallobservers-do-not-work/4796/3 "2020-12-11T12:03:25Z")
Very sorry for the unclearing question. I want to remove all observers and implement myself observers. I hope `interactor.RemoveAllObservers()` can remove all observers. If it work, nothing will happen for zoom in and pan operation (press left/right mouse and move). However, I find that the image still zoom in when I press the left mouse and move.
Also, the following code works:
```auto
self.vtkWidget = QVTKRenderWindowInteractor()
layout.addWidget(self.vtkWidget)
self.ren = vtk.vtkRenderer()
self.vtkWidget.GetRenderWindow().AddRenderer(self.ren)
interactor = self.vtkWidget.GetRenderWindow().GetInteractor()
interactor.Initialize()
self.imageViewer = vtk.vtkImageViewer2()
self.imageViewer.SetupInteractor(interactor)
self.imageViewer.SetRenderWindow(self.vtkWidget.GetRenderWindow())
img = vtk.vtkDICOMImageReader()
img.SetFileName('C:\\Users\\MLoong\\Desktop\\dicom_data\\Chang Cheng\\TOF\\IM_0174')
img.Update()
self.imageViewer.SetInputData(img.GetOutput())
self.imageViewer.Render()
interactor.RemoveAllObservers()
interactor.AddObserver('MouseMoveEvent', mouseMoveEvent)
interactor.Start()
```
However, I need to firstly create interactor the myself observer, and then (click a button) create the imageviewer. So, is there any method to `RemoveAllObservers` before `imageViewer.SetupInteractor(interactor)` ?