def set_axes_style(self, style=None, delay_draw=False):
        """set axes style: one of
           'box' / 'fullbox'  : show all four axes borders
           'open' / 'leftbot' : show left and bottom axes
           'bottom'           : show bottom axes only
        """
        if style is not None:
            self.axes_style = style
        axes0 = self.canvas.figure.get_axes()[0]
        _sty = self.axes_style.lower()
        if  _sty in ('fullbox', 'full'):
            _sty = 'box'
        if  _sty == 'leftbot':
            _sty = 'open'

        if _sty == 'box':
            axes0.xaxis.set_ticks_position('both')
            axes0.yaxis.set_ticks_position('both')
            axes0.spines['top'].set_visible(True)
            axes0.spines['right'].set_visible(True)
        elif _sty == 'open':
            axes0.xaxis.set_ticks_position('bottom')
            axes0.yaxis.set_ticks_position('left')
            axes0.spines['top'].set_visible(False)
            axes0.spines['right'].set_visible(False)
        elif _sty == 'bottom':
            axes0.xaxis.set_ticks_position('bottom')
            axes0.spines['top'].set_visible(False)
            axes0.spines['left'].set_visible(False)
            axes0.spines['right'].set_visible(False)
        if not delay_draw:
            self.canvas.draw()
set axes style: one of
           'box' / 'fullbox'  : show all four axes borders
           'open' / 'leftbot' : show left and bottom axes
           'bottom'           : show bottom axes only