menu-bar-update-hook is a variable defined in `C source code'.
Its value is
(menu-bar-update-buffers)
This variable may be risky if used as a file-local variable.
Documentation:
Normal hook run to update the menu bar definitions.
Redisplay runs this hook before it redisplays the menu bar.
This is used to update menus such as Buffers, whose contents depend on
various data.