def _qt4_on_destroyed(self, control=None):
        self.control = None
Test if saving a visualization and restoring it works.
dataset/ETHPy150Open enthought/pyface/pyface/ui/qt4/action/action_item.py/_MenuItem._qt4_on_destroyed--crossover with--dataset/ETHPy150Open enthought/mayavi/mayavi/tests/test_image_data_reader.py/TestDEMImageReader.test_save_and_restore