Here is a complete example of defining a menu keymap. It is the definition of the ‘Replace’ submenu in the ‘Edit’ menu in the menu bar, and it uses the extended menu item format (see Extended Menu Items). First we create the keymap, and give it a name:
(defvar menu-bar-replace-menu (make-sparse-keymap "Replace"))
Next we define the menu items:
(define-key menu-bar-replace-menu [tags-repl-continue]
'(menu-item "Continue Replace" multifile-continue
:help "Continue last tags replace operation"))
(define-key menu-bar-replace-menu [tags-repl]
'(menu-item "Replace in tagged files" tags-query-replace
:help "Interactively replace a regexp in all tagged files"))
(define-key menu-bar-replace-menu [separator-replace-tags]
'(menu-item "--"))
;; …
Note the symbols which the bindings are made for; these appear
inside square brackets, in the key sequence being defined. In some
cases, this symbol is the same as the command name; sometimes it is
different. These symbols are treated as function keys, but they are
not real function keys on the keyboard. They do not affect the
functioning of the menu itself, but they are echoed in the echo area
when the user selects from the menu, and they appear in the output of
where-is and apropos.
The menu in this example is intended for use with the mouse. If a menu is intended for use with the keyboard, that is, if it is bound to a key sequence ending with a keyboard event, then the menu items should be bound to characters or real function keys, that can be typed with the keyboard.
The binding whose definition is ("--") is a separator line.
Like a real menu item, the separator has a key symbol, in this case
separator-replace-tags. If one menu has two separators, they
must have two different key symbols.
Here is how we make this menu appear as an item in the parent menu:
(define-key menu-bar-edit-menu [replace] (list 'menu-item "Replace" menu-bar-replace-menu))
Note that this incorporates the submenu keymap, which is the value of
the variable menu-bar-replace-menu, rather than the symbol
menu-bar-replace-menu itself. Using that symbol in the parent
menu item would be meaningless because menu-bar-replace-menu is
not a command.
If you wanted to attach the same replace menu to a mouse click, you can do it this way:
(define-key global-map [C-S-down-mouse-1] menu-bar-replace-menu)