title: How to thread wxPython progress bar
body: <p>I'm trying to thread wx.ProgressDialog. I got a Progress threading class </p>
  
  <pre><code>class Progress(threading.Thread):
      def __init__(self):
          threading.Thread.__init__(self)
      def run(self):
          max = 1000000
  
          dlg = wx.ProgressDialog("Progress dialog example",
                                 "An informative message",
                                 maximum = max,
                                 parent=None,
                                 style = wx.PD_CAN_ABORT
                                  | wx.PD_APP_MODAL
                                  | wx.PD_ELAPSED_TIME
                                  | wx.PD_ESTIMATED_TIME
                                  | wx.PD_REMAINING_TIME
                                  )
          keepGoing = True
          count = 0
  
          while keepGoing and count &lt; max:
              count += 1
              wx.MilliSleep(250)
  
              if count &gt;= max / 2:
                  (keepGoing, skip) = dlg.Update(count, "Half-time!")
              else:
                  (keepGoing, skip) = dlg.Update(count)
          dlg.Destroy()
  </code></pre>
  
  <p>which gets called when I push a button by</p>
  
  <pre><code>class MiPPanel ( wx.Panel ):
      [...]
      def runmiP(self, event):
          thread1 = Progress() 
          thread1.start() 
  </code></pre>
  
  <p>When I run thread1.start() I get 100s of warnings of the type <code>2012-12-01 00:31:19.215 Python[3235:8807] *** __NSAutoreleaseNoPool(): Object 0x11a88f300 of class NSConcreteAttributedString autoreleased with no pool in place - just leaking
  </code> and the progress bar doesn't show up.</p>
  
  <p>How can I use threading with wxPython to make a progress bar?</p>