Watercolor

Watercolor (also known as Business or Professional) is the name of a placeholder visual style created by Microsoft during development of the Windows XP operating system.

Contrary to popular belief, the first known build to include it was build 2223; however, there was no user interface to enable it and it was largely incomplete. By build 2250, the Desktop control panel was enhanced to support the new visual styles and as a result, many mistakenly consider it to be the first build to include the visual style. The last known build to include the Watercolor theme was build 2419.

The early variant of the Watercolor visual style used in build 2223 was a dark blue and gray theme that was reminiscent of the classic theme used by Windows 2000 and earlier. This was later changed around build 2257 to use brighter shades of blue with red frames for disabled windows. The embedded  also includes a commented out section for a Champagne color scheme, which was likely used for testing purposes prior to build 2250 but is not functional in any known build:

Although the theme was removed from Windows XP after the introduction of Luna, it was still included in the source code of both Windows XP and Windows Server 2003.