def relabel(self, xlabel=None, ylabel=None,
                y2label=None, title=None, delay_draw=False):
        " re draw labels (title, x, y labels)"
        n = self.labelfont.get_size()
        self.titlefont.set_size(n+1)
        # print("  plot relabel ", delay_draw)
        rcParams['xtick.labelsize'] =  rcParams['ytick.labelsize'] =  n
        rcParams['xtick.color'] =  rcParams['ytick.color'] =  self.textcolor

        if xlabel is not None:
            self.xlabel = xlabel
        if ylabel is not None:
            self.ylabel = ylabel
        if y2label is not None:
            self.y2label = y2label
        if title is not None:
            self.title = title

        axes = self.canvas.figure.get_axes()
        kws = dict(fontproperties=self.titlefont, color=self.textcolor)
        axes[0].set_title(self.title, **kws)
        kws['fontproperties'] = self.labelfont

        if len(self.xlabel) > 0 and self.xlabel not in ('', None, 'None'):
            axes[0].set_xlabel(self.xlabel, **kws)

        if len(self.ylabel) > 0 and self.ylabel not in ('', None, 'None'):
            axes[0].set_ylabel(self.ylabel, **kws)
        if (len(axes) > 1 and len(self.y2label) > 0 and
            self.y2label not in ('', None, 'None')):
            axes[1].set_ylabel(self.y2label, **kws)

        for ax in axes[0].xaxis, axes[0].yaxis:
            for t in (ax.get_ticklabels() + ax.get_ticklines()):
                t.set_color(self.textcolor)
                if hasattr(t, 'set_fontsize'):
                    t.set_fontsize(n)

        self.set_added_text_size()
        if self.mpl_legend is not None:
            for t in self.mpl_legend.get_texts():
                t.set_color(self.textcolor)
        if not delay_draw:
            self.canvas.draw()
re draw labels (title, x, y labels)