thread timing issues with CallAfter

blammo.py

"""
Typical failure, about 70% of the time on a Debian Squeeze 32bit VM (in VirtualBox, with Debian Squeeze 64bit host OS).

Exception in thread Thread-1:
Traceback (most recent call last):
  File "/opt/sw/32bit/debian/python/2.7.3/lib/python2.7/threading.py", line 551, in __bootstrap_inner
    self.run()
  File "blammo.py", line 49, in run
    myappMainFrame.loginThread.boo = 42
AttributeError: 'MyAppMainFrame' object has no attribute 'loginThread'
"""


import sys
import wx
import threading
import os
import time

global myappMainFrame
myappMainFrame = None

class MyAppMainFrame(wx.Frame):
    def __init__(self, parent, id, title):
        wx.Frame.__init__(self, parent, id, title, style=wx.DEFAULT_FRAME_STYLE ^ wx.RESIZE_BORDER)
        self.loginDialogPanel = wx.Panel(self, wx.ID_ANY)
        self.loginDialogPanelSizer = wx.FlexGridSizer(rows=2, cols=1, vgap=15, hgap=5)

        self.buttonsPanel = wx.Panel(self.loginDialogPanel, wx.ID_ANY)
        self.buttonsPanelSizer = wx.FlexGridSizer(rows=1, cols=3, vgap=5, hgap=10)
        self.buttonsPanel.SetSizer(self.buttonsPanelSizer)

        LOGIN_BUTTON_ID = 1
        self.loginButton = wx.Button(self.buttonsPanel, LOGIN_BUTTON_ID, 'Login')
        self.buttonsPanelSizer.Add(self.loginButton, flag=wx.TOP|wx.BOTTOM|wx.LEFT|wx.RIGHT, border=10)
        self.Bind(wx.EVT_BUTTON, self.onLogin, id=LOGIN_BUTTON_ID)

        self.buttonsPanel.SetSizerAndFit(self.buttonsPanelSizer)
        self.loginDialogPanelSizer.Add(self.buttonsPanel, flag=wx.ALIGN_RIGHT|wx.BOTTOM|wx.LEFT|wx.RIGHT, border=15)

        self.loginButton.SetDefault()
        self.loginDialogPanel.SetSizerAndFit(self.loginDialogPanelSizer)
        self.loginDialogPanel.Layout()

        self.Fit()
        self.Layout()
        self.Centre()

    def onLogin(self, event):
        class LoginThread(threading.Thread):
            def __init__(self, notify_window):
                threading.Thread.__init__(self)
                self._notify_window = notify_window
                self.start()

            def do_something(self):
                print 'in do_something'
                return

            def run(self):
                # Comment out this time.sleep call and everything's ok
                # time.sleep(1)
                myappMainFrame.loginThread.boo = 42
                wx.CallAfter(self.do_something)
                os._exit(0)

        self.loginThread = LoginThread(self)

class MyApp(wx.App):
    def OnInit(self):

        global myappMainFrame
        myappMainFrame = MyAppMainFrame(None, wx.ID_ANY, ' ')
        myappMainFrame.Show(True)
        return True

app = MyApp(False)
app.MainLoop()