vtkInteractorObserver destructor calls virtual function SetEnabled
This issue was created automatically from an original Mantis Issue. Further discussion may take place here.
virtual function SetEnabled is called in the destructor of vtkInteractorObserver. From debug, it just calls empty function in vtkInteractorObserver.
As we know, from http://www.artima.com/cppsource/nevercall.html Never call virtual functions during construction or destruction.
It's better to remove this call. I guess SetEnabled(0) will be called in sub-class destructor.