get-checkable-menu-item% in frame:standard-menus<%>
The result of this method is used as the class for creating
checkable menu items in this class (see
frame:standard-menus% for a list).
(-> (derived-fromsenda-frame:standard-menusget-checkable-menu-item%)checkable-menu-item%)defaultly returns
menu:can-restore-checkable-menu-item%.