[vtkusers] Program crashing because vtkContourWidget still getting sent events after it's deleted.

[kent williams]

My tracing application is crashing.  It crashes when I delete an
instance of vtkContourWidget.

The problem is that as soon as any event happens in the window which
the vtkContourWidget was associated, the event still gets invoked on
the deleted instance.

I.e. the problem happens when I mouse movement event is sent to the
vtkGenericRenderWindowInteractor.

It is as though I need some sort of method to disassociate the
vtkContourWidget from the RenderWindowInteractor before I delete it.

Either that or vtkContourWidget needs to start doing this in its
destructor/Delete method.

Anyone know if this is a bug, or if I'm just doing things wrong?