EXCLUSIVE BetaNews has learned that Thursday's leak of the Windows 2000 source code originated not from Microsoft, but from long-time Redmond partner Mainsoft. The leaked code includes 30,915 files and was apparently removed from a Linux computer used by Mainsoft for development purposes. Dated July 25, 2000, the source code represents Windows 2000 Service Pack 1. Analysis indicates files within the leaked archive are only a subset of the Windows source code, which was licensed to Mainsoft for use in the company's MainWin product. MainWin utilizes the source to create native Unix versions of Windows applications. Mainsoft says it has...