set panel layout

def set_layout(self):
        """ set panel layout
        """
        sizer = wx.BoxSizer(wx.VERTICAL)
        sizer.Add(self.canvas, 1, wx.EXPAND)
        hbox = wx.BoxSizer(wx.HORIZONTAL)
        if self.toolbar is not None:
            self.toobar = MyToolbar(self.canvas)
            self.toobar.Realize()
            hbox.Add(self.toobar, 0, wx.EXPAND | wx.RIGHT, 10)
        self.pos_st = wx.StaticText(self, label='')
        hbox.Add(self.pos_st, 0, wx.ALIGN_CENTER_VERTICAL)
        sizer.Add(hbox, 0, wx.EXPAND | wx.BOTTOM, 0)
        self.SetSizerAndFit(sizer)