Menu bar
The menu bar's purpose is to supply a common housing for window- or application-specific menus which provide access to such functions as opening files, interacting with an application, or displaying help documentation or manuals.
Menu bars are typically present in graphical user interfaces that display documents and representations of files in windows and windowing systems but menus can be used as well in command-line interface programs like text editors or file managers where drop-down menu is activated with a shortcut or combination key.
Apple experiments in GUI design for the Lisa project initially used multiple menu bars anchored to the bottom of windows, but this was quickly dropped in favor of the current arrangement,[1] as it proved slower to use (in accordance with Fitts's law).
The Unity desktop shell shipped with Ubuntu Linux from version 11.04 through 17.04 uses a Macintosh-style menu bar; however, it is hidden unless the mouse pointer hovers over it, similar to the Amiga interface.
Window manager menus in Linux are typically configurable by editing text files or using a desktop-environment-specific Control Panel applet.
The title/menu bar would typically sit at the top of the screen, and could be accessed by pressing the right mouse button, revealing the names of the various menus.
When the right menu button was not pressed down, the menu/title bar would typically display the name of the program which owned the screen, and some other information such as the amount of memory used.
The NeXTstep OS for the NeXT machines would display a "menu palette", by default at the top left of the screen.
The TOS operating system for the Atari ST would display menu bars at the top of the screen like Mac OS.
In RISC OS, clicking the middle button displays a menu list at the location of the mouse pointer.
In both Windows and Macintosh operating systems, in other similar desktop environments and in some applications, common functions are assigned keyboard shortcuts (e.g. Control-C or Command-C copies the current selection).
The effectiveness of this technique is also reduced on larger screens or with low mouse acceleration curves, especially due to the time required to travel back to a target in the window after using the menu.
