Updates font style widget

        Parameters
        ----------

        font_style: Integer
        \tButton down iif font_style == wx.FONTSTYLE_ITALIC

def _update_font_style(self, font_style):
        """Updates font style widget

        Parameters
        ----------

        font_style: Integer
        \tButton down iif font_style == wx.FONTSTYLE_ITALIC

        """

        toggle_state = font_style & wx.FONTSTYLE_ITALIC == wx.FONTSTYLE_ITALIC

        self.ToggleTool(wx.FONTFLAG_ITALIC, toggle_state)