simple_window.py

import wx


class MyPanel(wx.Panel):
    """"""

    def __init__(self, parent):
        """Constructor"""
        wx.Panel.__init__(self, parent)

class MyFrame(wx.Frame):
    """"""

    def __init__(self):
        """Constructor"""
        wx.Frame.__init__(self, parent=None, title="Add Buttons")
        
        panel = MyPanel(self)
        self.Show()


if __name__ == "__main__":
    app = wx.App(False)
    frame = MyFrame()
    app.MainLoop()

simpler_window.py

import wx
   

class MyFrame(wx.Frame):
    """"""

    def __init__(self):
        """Constructor"""
        wx.Frame.__init__(self, parent=None)
        self.SetTitle("Add Buttons")
        self.fSizer = wx.BoxSizer(wx.VERTICAL)
        
        panel = wx.Panel(self)
        self.Show()


if __name__ == "__main__":
    app = wx.App(False)
    frame = MyFrame()
    app.MainLoop()