'Tear down an instance of :class:`CanvasScene` that was used by the
editor.'

def __teardownScene(self, scene):

    scene.clearSelection()
    scene.setFocusItem(None)
    self.__annotationGeomChanged.deleteLater()
    self.__annotationGeomChanged = None
    self.__focusListener.itemFocusedIn.disconnect(self.__onItemFocusedIn)
    self.__focusListener.itemFocusedOut.disconnect(self.__onItemFocusedOut)
    scene.selectionChanged.disconnect(self.__onSelectionChanged)
    scene.removeEventFilter(self)
    scene.blockSignals(True)
    scene.clear_scene()
