def keyPressEvent(self, ev):
if ev.key() == QtCore.Qt.Key_Up:
if self.pick_radius > -1:
self.pick_radius += 1
if ev.key() == QtCore.Qt.Key_Down:
if self.pick_radius > 0:
self.pick_radius -= 1
QVTKRenderWindowInteractor.keyPressEvent(self, ev)
