I would use a wx.Timer() object. You can set the timer to run for X number of milliseconds and then the event it is attached to will fire and you can clear the status bar's text and stop the timer too.
So you'd do something like this:
self.timer = wx.Timer(self)
self.Bind(wx.EVT_TIMER, self.clearStatus, self.timer)
self.timer.Start(10000) # fire in 10 seconds
Then in your handler, you'd do something like this:
def clearStatus(self, event):
self.SetStatusText("")
self.timer.Stop()
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