from wxPython.wx import *

class MiaApp(wxApp):
    def OnInit(self):
        dlg = wxDialog(None, -1, "", size=(200,100))

        ID_RBOX = wxNewId()
        rb = wxRadioBox(dlg, ID_RBOX, "Scegli:",
                        choices=["ciao", "mondo", "!"])
        EVT_RADIOBOX(self, ID_RBOX, self.OnEvtRadio)
        # imposta la selezione al SECONDO pulsante,
        # l'indice parte da zero!
        rb.SetSelection(1)

        dlg.ShowModal()
        dlg.Destroy()
        return 1

    def OnEvtRadio(self, event):
        wxMessageBox("OnEvtRadio: %i" % event.GetInt())

app = MiaApp()
app.MainLoop()