From GNUstepWiki

GNUStep provides 3 menus. The system menu, the contextual menu, and the window menu. Their behaviours are not specifically defined, however the observed behaviour is.

Under linux

  • If a context menu is available when right clicking provide it, if not provide the application menu, otherwise provide the system menu.

Under MacOS X

  • If a context menu is available provide it, applications menus appear in the menubar at the top of the screen according to the application in the foreground.

Under Windows