def doLayout(self):
    gridsizer = wx.GridSizer(2, 3, vgap = 10, hgap = 20)
    boxsizer = wx.BoxSizer (wx.VERTICAL)

    buttons_list = [wx.Button (self, id = wx.NewId(), label = "Button " + str(n) ) for n in range (6)]

    for button in buttons_list:
        gridsizer.Add (button)

    boxsizer.Add (gridsizer)

    self.SetSizer(boxsizer)
    self.Layout()