Function: menu-bar-mode

Toggle display of a menu bar on each frame (Menu Bar mode).
With a prefix argument ARG, enable Menu Bar mode if ARG is
positive, and disable it otherwise. If called from Lisp, enable
Menu Bar mode if ARG is omitted or nil.

This command applies to all frames that exist and frames to be
created in the future.

Variable: menu-bar-mode

Non-nil if Menu-Bar mode is enabled.
See the command `menu-bar-mode' for a description of this minor mode.
Setting this variable directly does not take effect;
either customize it (see the info node `Easy Customization')
or call the function `menu-bar-mode'.