Called when the user activates a reader in the toolbar combo box.

def OnReaderComboBox(self, event):
        """Called when the user activates a reader in the toolbar combo box."""
        cb = event.GetEventObject()
        reader = cb.GetClientData(cb.GetSelection())
        if isinstance(reader, smartcard.reader.Reader.Reader):
            self.treeuserpanel.dialogpanel.OnActivateReader(reader)