Enable smooth edges if utf-8 is supported

def on_unicode_checkbox(self, w=None, state=False):
        """Enable smooth edges if utf-8 is supported"""
        logging.debug("unicode State is %s", state)

        # Update the controller to the state of the checkbox
        self.controller.smooth_graph_mode = state
        if state:
            self.hline = urwid.AttrWrap(
                urwid.SolidFill(u'\N{LOWER ONE QUARTER BLOCK}'), 'line')
        else:
            self.hline = urwid.AttrWrap(urwid.SolidFill(u' '), 'line')

        for graph in self.graphs.values():
            graph.set_smooth_colors(state)

        self.show_graphs()