edit-menu:undo-on-demand

The menu item's on-demand method calls this method

• (send a-frame:standard-menus edit-menu:undo-on-demand item) -> void
      item : menu-item%

  Defaultly is this:

    (lambda (item) (let* ((editor (get-edit-target-object)) (enable? (and editor (is-a? editor editor<%>) (send editor can-do-edit-operation? (quote undo))))) (send item enable enable?)))