[vtkusers] c# custom interactor exception "could not get registered type - mteIndex='4294967295' "

[The Merper]

Hi all,
  I'm trying to create a vtkInteractorStyleImage with a custom right button
press event like so:

vtkInteractorStyleImage interactorStyle = vtkInteractorStyleImage.New();
interactorStyle.RightButtonPressEvt += new vtkObject.vtkObjectEventHandler(
MyRightButtonPress);
vtkCellPicker Picker = vtkCellPicker.New();
RenWin.GetInteractor().SetPicker(Picker);
RenWin.GetInteractor().SetInteractorStyle(interactorStyle);

The interactor works, but sometimes when I use it, I get the following
exception:

could not get registered type - mteIndex='4294967295' classNameKey=''

According to this thread:
https://public.kitware.com/pipermail/vtkusers/2013-April/079120.html

The problem is that I need to remove to default RightButtonPressEvt before
I add my custom event. How can I do this?
    thank you in advance for any help you can offer,
         -Merps
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