Plex

Plex was the main visual style for earlier builds of Windows Longhorn. It was featured as the default theme from builds 3683 to 4042 (main). It features an almost all-blue user interface with a prototype sidebar. The theme was removed for build 4042 (Lab06_n) and replaced with Slate: the development team never intended for Plex to become a finalized theme[source?]; it was intended as a placeholder for the Aero theme which ended up in the final version of Windows Vista.