Why does not my wx.html.HtmlWindow work?

[liqfemail at gmail.com]

Below are my source code:

import wx
import wx.html

class MyHtmlFrame(wx.Frame):

    def __init__(self, parent, title):
        wx.Frame.__init__(self, parent, -1, title, size=(600,400))
        html = wx.html.HtmlWindow (self)
        if "gtk2" in wx.PlatformInfo:
            html.SetStandardFonts()
        html.LoadPage(" http://www.pythonthreads.com/articles/python/incorporating-into-wxpython-part-1.html")

app = wx.PySimpleApp()
frm = MyHtmlFrame(None, "Simple HTML Browser")
frm.Show()
app.MainLoop()

It is just an example in the book "wxPython in action". But every time
when I try to get it run, my CPU is fully occupied, and there is no
frame that comes into existence. Why?