A menu-bar% object is created for a particular frame% object. A frame can have at most one menu bar; an exn:fail:contract exception is raised when a new menu bar is created for a frame that already has a menu bar.
Creates a menu bar in the specified frame. The menu bar is initially empty. If 'root is supplied as parent, the menu bar becomes active only when no other frames are shown. A 'root parent is allowed only when current-eventspace-has-menu-root? returns #t, and only if no such menu bar has been created before, otherwise an exn:fail:contract exception is raised.
The demand-callback procedure is called by the default on-demand method with the object itself.
Enables or disables the menu bar (i.e., all of its menus). Each menu’s is-enabled? method returns #f only if the menu is specifically disabled (in addition to the menu bar).
Returns the menu bar’s frame.
Returns #t if the menu bar is enabled, #f otherwise.