Desktop Window Manager is always
- Windows 8
Servers - Windows Server 2012
In Windows 8, Desktop Window Manager (DWM) is always ON and cannot be disabled by end users and apps.
As in Windows 7, DWM is used to compose the desktop. In addition to experiences enabled in Windows 7, now DWM desktop composition enables desktop composition for all themes, support for Stereoscopic 3D, and management, separation, and protection of the experience with Windows Store apps.
Desktop composition for all themes
In Windows Vista and Windows 7, desktop composition is enabled only with the AERO Glass Theme. Hence users of Windows Classic and high contrast themes cannot use experiences enabled by desktop composition such as Windows Flip, automatic scaling for high resolution (DPI) scaling, thumbnail Preview and full screen magnifier. In addition, in these earlier versions of Windows, app developers must write and maintain multiple code paths - one where desktop composition is enabled and another where desktop composition is disabled.
With Windows 8, desktop composition is enabled for all themes. Users of Windows Classic and high contrast themes can use the experiences enabled by desktop composition such as Windows Flip, automatic scaling for high resolution (DPI) scaling, thumbnail previews, and full screen magnifier. In addition, developers don't need to write and maintain multiple code paths, thereby simplifying development.