import wx

app = wx.PySimpleApp()
frame = wx.Frame(None, title="Sizers")

sizer = wx.BoxSizer(wx.VERTICAL)

label1 = wx.StaticText(parent=frame, id=-1, label="Hello, world!")
label2 = wx.StaticText(parent=frame, id=-1, label="How's it going?")
buttons = [wx.Button(frame, -1, "Button %s" % (n + 1)) for n in range(3)]

sizer.Add(label1)
sizer.Add(label2)
for button in buttons:
    sizer.Add(button)

frame.SetSizer(sizer)

frame.Show()
app.MainLoop()