Simple wxPython AUI frame that crashes.

#!/usr/bin/env python
# Encoding: UTF-8
"""This script launches a GUI for testing regular expressions."""

import sys
import os
import re

try:
    import wx
except ImportError:
    print "This script requires wxPython."
    sys.exit(1)

class RegexTesterFrame(wx.Frame):
    def __init__(self):
        wx.Frame.__init__(
            self, None, -1, 'Regex tester', (100, 100),
            (400, 400), wx.DEFAULT_FRAME_STYLE
        )
        # wx.Frame.__init__(
        #     self, None, -1, 'Regex tester', wx.DefaultPosition,
        #     wx.DefaultSize, wx.DEFAULT_FRAME_STYLE
        # )

        self.initialize_components()
        self.CreateStatusBar()

    def initialize_components(self):
        self._mgr = wx.aui.AuiManager()
        self._mgr.SetManagedWindow(self)

        self._perspectives = []

        self._mgr.AddPane(
            wx.CheckBox(self, -1, 'test'),
            wx.aui.AuiPaneInfo().Name('Test pane').Caption('Test caption').Top()
        )

        self._mgr.Update()

        self.Bind(wx.EVT_CLOSE, self.on_close)

        # self.create_flags_panel()

    def on_close(self, event):
        self._mgr.UnInit()
        del self._mgr
        self.Destroy()

    # def create_flags_panel(self):
    #     panel = wx.Panel(self, -1, style=wx.FULL_REPAINT_ON_RESIZE)

    #     sizer = wx.GridBagSizer(0, 5)
    #     sizer.Add(wx.CheckBox(panel, -1, 'Global'), (0, 0))
    #     sizer.Add(wx.CheckBox(panel, -1, 'Ignore case'), (0, 1))
    #     sizer.Add(wx.CheckBox(panel, -1, 'Ignore whitespace'), (0, 2))
    #     sizer.Add(wx.CheckBox(panel, -1, 'Multiline'), (0, 3))

    #     panel.SetSizerAndFit(sizer)

    #     return panel

class RegexTesterApp(wx.App):
    def OnInit(self):
        mainframe = RegexTesterFrame()
        mainframe.Show()

        self.SetTopWindow(mainframe)
        return True

def main():
    app = RegexTesterApp(True)
    app.MainLoop()

if __name__ == '__main__':
    main()