When a screen saver starts, the startup code in the screen saver library creates a full-screen window. The screen saver library contains the main function and other startup code required for a screen saver. Screen savers contain specific exported functions, resource definitions, and variable declarations. Windows Vista and later: If password protection is enabled by policy, the screen saver is started regardless of what an application does with the SC_SCREENSAVE notification. The security context determines the level of privileged operations which can be done from a screen saver.

Windows 2003 - screen saver runs in the context of LocalService with all privileges removed and administrators group disabled.

Windows XP and Windows 2000 - screen saver runs in the context of LocalSystem with accounts restricted.

If no user is logged on, the security context of the screen saver is dependent on the version of Windows being used. If a user is interactively logged on when the screen saver is invoked, the screen saver runs in the security context of the interactive user. The security context of the screen saver is dependent on whether a user is interactively logged on.

The active application receives the WM_SYSCOMMAND message with the wParam parameter set to the SC_SCREENSAVE value, but it does not pass the message to the DefWindowProc function.

A computer-based training (CBT) window is present.

The active application is not a Windows-based application.

However, Windows does not start the screen saver if any of the following conditions exist: Once a screen saver is chosen, Windows monitors keystrokes and mouse movements and then starts the screen saver after a period of inactivity. Screen savers are loaded automatically when Windows starts or when a user activates the screen saver through the Control Panel. The Desktop application in the Windows Control Panel lets users select from a list of screen savers, specify how much time should elapse before the screen saver starts, configure screen savers, and preview screen savers.

Adding Help to the Screen Saver Configuration Dialog Box.

This topic is divided into the following sections.

To conceal sensitive information left on a screen.

To protect a screen from phosphor burn caused by static images.

Screen savers start when the mouse and keyboard have been idle for a specified period of time. The Microsoft Win32 API supports special applications called screen savers.

App to play screensaver scr file