If you're running in a graphical environment such as Windows, your program controls the general layout and contents of the menu. The environment controls the look of the menu and handles most of the user's interaction with it.
Windows and Windows NT menu bars are static in that they display continually until your program removes them. They are shown horizontally along the top edge of your application's window. They exist outside of your program's screen — you don't need to allow space for the menu bar when creating your application. A menu can contain submenus that pull down vertically when the user selects them. The submenus may contain further submenus, which Windows handles as pop-up menus.