# File gtk/sample/gtk-demo/tree_store.rb, line 254
    def item_toggled (cell, path_str, model)
      path = Gtk::TreePath.new(path_str)

      column = cell.column

      # get toggled iter
      iter = model.get_iter(path)
      toggle_item = iter[column]

      # do something with the value
      toggle_item ^= 1

      # set new value
      iter[column] = toggle_item
    end