current-eventspace-has-standard-menus? in System Menus
Returns #t for Mac OS X when the current eventspace is the
initial one, since that eventspace is the target for the standard
application menus. For any other system or eventspace, the result is
#f.
This procedure is intended for use in deciding whether to include a
Quit, About, and Preferences menu
item in a frame's menu. Under Mac OS X, the application
Quit menu triggers a call to a frame's
on-exit method, the About menu item is controlled by
application-about-handler, and the
Preferences menu item is controlled by
application-preferences-handler.