[vtkusers] Calling a custom function when terminating vtkRenderWindowInteractor

[Phil Goddard]

I'm wondering if someone can explain to me how to call my own custom
function when q or e is pressed on a vtkRenderWindowInteractor.

The doc for vtkRenderWindowInteractor::TerminateApp says
"This function is called on 'q','e' keypress if exitmethod is not specified
and should be overridden by platform dependent subclasses to provide a
termination procedure if one is required."

However there is no mention (that I can see) of how to specify an
exitmethod.