Desktop Window Manager

The Desktop Composition Engine (or DCE) is a theme rendering engine used in early builds of Windows Longhorn. It is present starting with build 3683, but in a buggy state that only renders windows transparency. From build 3706 thru builds 4001, a new twirling windows effect when minimizing or closing is added. On build 4011 and 4015, DCE only provides transparency effects. It is required in order to enable Windows Aero on build 4039 and 4042. It synchronized with WinFS, Avalon, and other internal Windows databases, as well as providing visual effects.

Starting with build 4066, the DCE was replaced by Desktop Window Manager.