def onSceneStartClose(self, caller, event):
        """
        Called just before the scene is closed.
        """
        self._turninig = True
        # Parameter node will be reset, do not use it anymore
        self.saveProgress()

        self.setParameterNode(None)
        self.resetPointList(
            self.ui.dgPositiveControlPointPlacementWidget,
            self.dgPositivePointListNode,
            self.dgPositivePointListNodeObservers, )
        self.dgPositivePointListNode = None
        self.resetPointList(
            self.ui.dgNegativeControlPointPlacementWidget,
            self.dgNegativePointListNode,
            self.dgNegativePointListNodeObservers, )
        self.dgNegativePointListNode = None

        Called just before the scene is closed.
        
EISeg/med3d/EISegMed3D/EISegMed3D.py