wx.ProgressDialog disappears

The progress dialog disappers rather then the cancel button changing to a close button when it is to be destroyed (and the PD_AUT开发者_JS百科O_HIDE flag is not set).

    progressDlg = wx.ProgressDialog("Organizing music files",
                                        "This may take some time..",
                                        maximum=9999,
                                        parent=self,
                                        style = wx.PD_CAN_ABORT
                                        |wx.PD_APP_MODAL
                                        |wx.PD_ELAPSED_TIME)
                                        )

    progressDlg.SetSize((400, 200))
    while self.working:
        wx.MilliSleep(250)
        progressDlg.Pulse(os.getcwd())
    progressDlg.Destroy()

Destroy() explicitly deletes the actual control. I'm pretty sure Destroy()ing a progressdialog behaves as every other control