Called when a reader is selected by clicking on the
        reader tree control or toolbar.

def OnSelectReader(self, reader):
        """Called when a reader is selected by clicking on the
        reader tree control or toolbar."""
        SimpleSCardAppEventObserver.OnSelectReader(self, reader)
        self.feedbacktext.SetLabel('Selected reader: ' + repr(reader))
        self.transmitbutton.Disable()