About Face 2.0(c) The Essentials of Interaction Design

The system menu is a Windows standard menu available in the upper-left corner of all independent windows, which replicates window frame controls. In Windows 3x, there was a little box with a horizontal bar in it that launched this menu. In Windows 95 and later, this was replaced by the program's icon. Some Unix GUI platforms, like Motif, have a similar menu, in a similar location.

This menu is a relic. It serves no useful purpose. Originally, it was to be the home of system-level window management commands, but they have migrated to immediate controls on the title bar and window frame, and no new ones have been added.

The very existence of the window menu contributes to the level of ambient confusion; it's just another lever on the mechanism with no evident purpose except to generate worry in the user's mind. The sole remaining purpose for the system menu is as a programming support for equivalent keyboard commands for moving, resizing, maximizing, and minimizing the window. It would be no loss to the interface if the system menu were eliminated, as long as the keyboard commands were retained. Somehow it has been retained, even in Windows XP.