def apply(self):
        """Apply changes to the plots."""
        self.read_group_info()

        if self.tabs.count() == 0:
            # disactivate buttons
            self.button_color.setEnabled(False)
            self.button_del.setEnabled(False)
            self.button_apply.setEnabled(False)
        else:
            # activate buttons
            self.button_color.setEnabled(True)
            self.button_del.setEnabled(True)
            self.button_apply.setEnabled(True)

        if self.groups:
            self.parent.overview.update_position()
            self.parent.spectrum.update()
            self.parent.notes.enable_events()
        else:
            self.parent.traces.reset()
            self.parent.spectrum.reset()
            self.parent.notes.enable_events()
Apply changes to the plots.