def makeLabel(self):
        c_label = StretchingLabel()
        self.bind(pos=c_label.setter('pos'), width=c_label.setter('width'), c_description=c_label.setter('text'))

        # self.c_description = 'test'  # you should change value after bind to force update
        # or use dispatch() to fire update event manually:
        self.property('c_description').dispatch(self)

        # doc: https://kivy.org/doc/stable/api-kivy.properties.html#kivy.properties.Property.dispatch

        self.add_widget(c_label)