def OnInit(self):

    self.name = "SingleApp-%s" % wx.GetUserId()
    self.instance = wx.SingleInstanceChecker(self.name)

    if self.instance.IsAnotherRunning():
        wx.MessageBox("Another instance is running", "ERROR")
        return False

    frame = SingleAppFrame(None, "SingleApp")
    frame.Show()
    return True