VTK close event filter

VTKCloseEventFilter.py

class CloseEventFilter(QObject):
    def eventFilter(self, target, event):
        if event.type() == QEvent.Close:
            for w in target.children():
                if hasattr(w, 'close'):
                    w.close()
            return True
        return False

#Usage example:
#
#...
#qframe1 = QFrame()
#qframe2 = QFrame()
#qframe1.installEventFilter(ev_filter)
#qframe2.installEventFilter(ev_filter)
#vtk_interactor1 = QVTKRenderWindowInteractor(parent=qframe1)
#vtk_interactor2 = QVTKRenderWindowInteractor(parent=qframe2)
#...