code: def find_selected(self, event):
          '''find the selected menu item'''
          first = self.id()
          last = first + len(self.items) - 1
          evid = event.GetId()
          if evid >= first and evid <= last:
              self.choice = evid - first
              return self
          return Nonf find_selected(self, event):
          '''find the selected menu item'''
          first = self.id()
          last = first + len(self.items) - 1
          evid = event.GetId()
          if evid >= first and evid <= last:
              self.choice = evid - first
              return self
          return None
docs: find the selected menu item