code: def error_msg_wx(msg, parent=None):
      
      dialog =wx.MessageDialog(parent  = parent,
                               message = msg,
                               caption = 'Matplotlib backend_wx error',
                               style=wx.OK | wx.CENTRE)
      dialog.ShowModal()
      dialog.Destroy()
      return None
docs: Signal an error condition -- in a GUI, popup a error dialog