code: def OnNodeSelected(self, event):
          
          try:
              node = self.sorted[event.GetIndex()]
          except IndexError, err:
              log.warn(_('Invalid index in node selected: %(index)s'),
                       index=event.GetIndex())
          else:
              if node is not self.selected_node:
                  wx.PostEvent(
                      self,
                      squaremap.SquareSelectionEvent(node=node, point=None,
                                                     map=None)
                  )
docs: We have selected a node with the list control, tell the world