How to restore the mouse listener event

Hello:
every teachers, i uesd the code to define a new event about left mouse press event
image|690x282
but how can i restore the default action
this is my code
def onStartMark(self):
layoutManager = slicer.app.layoutManager()
threeDWidget = layoutManager.threeDWidget(0)
threeDView = threeDWidget.threeDView()
self.interactor = threeDView.interactorStyle().GetInteractor()
import copy
self.interactor1 = self.interactor
# self.defaultObserver = interactor.GetObserverMediator()
self.interactor.RemoveObservers(‘LeftButtonPressEvent’)
self.interactor.AddObserver(‘LeftButtonPressEvent’, self.onRightButtonPressed)
pointPicker = vtk.vtkPointPicker()
self.interactor.SetPicker(pointPicker)