Microsoft received a patent confirmation that hands the company the intellectual property of "shutting an operating system down". In Aug 2005, Microsoft filed for a patent to more efficiently shut down its Windows OS as well as other OS, including Apple's Mac OS X, and override running programs that may prevent Windows from closing. That particular feature has been implemented for some time in Windows and is known as "notification screen" just before actual shutdown, if a user has requested Windows to close and other programs with open and unsaved documents are still running.
Microsoft describes this feature as "a user interface and scheme […] for facilitating shutting down an OS. Aspects include the OS receiving a command to initiate shut down, and automatically terminating graphical user interface (GUI) apps that delay shut down which don't have top level windows."