def METHOD_NAME(self, widget):
    old = dict(mix=np.copy(self._mix))
    self._mix = np.copy(self.std)
    new = dict(mix=np.copy(self._mix))
    self.pipeline.push(StageAction(self, old, new,
                                   descr="chmix / std grey"))
    if self.gui_up:
        self._gui_update_mix()
    self.pipeline.run_from(self)