Also, it's not just (allegedly) all of XP source that's been leaked:
https://www.bleepingcomputer.com/news/microsoft/the-windows-...
It's also Windows Server 2003, MS DOS 3.30, MS DOS 6.0, Windows 2000, Windows CE 3, Windows CE 4, Windows CE 5, Windows Embedded 7, Windows Embedded CE, Windows NT 3.5, and Windows NT 4!
That's a huge amount of stuff to analyse.