| The procedures for logging out, restarting the system, and shutting down the system have semantics similar to those for logging in. The foreground process usually initiates these procedures in response to the user choosing an item from the Apple menu; however, a process can also initiate the procedure programmatically by sending an appropriate Apple event to the loginwindow process. The loginwindow process carries out the procedure, posting alerts and notifying applications to give them a chance to clean up before closing.  A typical logout/restart/shutdown procedure is as follows: 1. | The user chooses Log Out, Restart, or Shut Down from the Apple menu.
| 2. | The foreground application initiates the user request by sending an Apple event to the loginwindow process.
| 3. | The loginwindow process displays an alert to the user asking for confirmation of the action.
| 4. | If the user confirms the action, loginwindow sends a Quit Application event (kAEQuitApplication) to every foreground and background user process.
NOTE An unresponsive application can prevent a user from logging out or shutting down the computer. After 45 seconds, loginwindow automatically aborts the termination sequence. In this case, force quit the application and try logging out or shutting down again. | 5. | The loginwindow process closes out the user session and continues with one of the following actions:
On a logout action, loginwindow dequeues all events in the event queue, starts the logout-hook program (if one is defined), records the logout, resets device permissions and user preferences to their defaults, and returns the user to the login window. On a restart, loginwindow sets the device permissions and user preferences to their defaults, powers off the system, and then powers it back on to start the startup process. On a shutdown, loginwindow powers off the computer.
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