BetaWiki:Featured article/2020-04
Sample Test Visual Style (internally known as Mallard) is a visual style included in some pre-release builds of Windows XP. As of 2020, the only leaked builds to include the style are Windows XP build 2410, 2416, and 2419, where it includes two color schemes, called Chartreuse Mongoose and Blue Lagoon (internally referred to as Paler).
A Whistler feature planning spreadsheet from 2000-02-22 mentions a default skin set consisting of a Consumer and Pro look planned to be finished by 2000-04-28, which refers to Watercolor (then-named Business) and possibly this theme as the string Personal Visual Style has been found in the theme files in early pre-Beta 2 builds.