Info Catalog elisp: Defining Menus elisp: Extended Menu Items

elisp: Simple Menu Items

 
 21.17.1.1 Simple Menu Items
 ...........................
 
 The simpler (and original) way to define a menu item is to bind some
 event type (it doesn’t matter what event type) to a binding like this:
 
      (ITEM-STRING . REAL-BINDING)
 
 The CAR, ITEM-STRING, is the string to be displayed in the menu.  It
 should be short—preferably one to three words.  It should describe the
 action of the command it corresponds to.  Note that not all graphical
 toolkits can display non-ASCII text in menus (it will work for keyboard
 menus and will work to a large extent with the GTK+ toolkit).
 
    You can also supply a second string, called the help string, as
 follows:
 
      (ITEM-STRING HELP . REAL-BINDING)
 
 HELP specifies a help-echo string to display while the mouse is on that
 item in the same way as ‘help-echo’ text properties (Help
 display).
 
    As far as ‘define-key’ is concerned, ITEM-STRING and HELP-STRING are
 part of the event’s binding.  However, ‘lookup-key’ returns just
 REAL-BINDING, and only REAL-BINDING is used for executing the key.
 
    If REAL-BINDING is ‘nil’, then ITEM-STRING appears in the menu but
 cannot be selected.
 
    If REAL-BINDING is a symbol and has a non-‘nil’ ‘menu-enable’
 property, that property is an expression that controls whether the menu
 item is enabled.  Every time the keymap is used to display a menu, Emacs
 evaluates the expression, and it enables the menu item only if the
 expression’s value is non-‘nil’.  When a menu item is disabled, it is
 displayed in a fuzzy fashion, and cannot be selected.
 
    The menu bar does not recalculate which items are enabled every time
 you look at a menu.  This is because the X toolkit requires the whole
 tree of menus in advance.  To force recalculation of the menu bar, call
 ‘force-mode-line-update’ (Mode Line Format).
 

Info Catalog elisp: Defining Menus elisp: Extended Menu Items