def doLayout(self):
    sizer = wx.BoxSizer(wx.VERTICAL)		

    btn1 = wx.Button (self, wx.NewId(), "Button 1")
    btn2 = wx.Button (self, wx.NewId(), "Button 2")

    sizer.Add (btn1, proportion = 1)
    sizer.Add (btn2, proportion = 1)

    self.SetSizer(sizer)
    self.Layout()