Earlier quoted context omitted.
If Apple open sourced all of macOS maybe that would put more pressure on Microsoft to intentionally[1] open source Windows. [1]: It has been open sourced in the past: https://torrentfreak.com/microsoft-takes-pirated-windows-nt-... http://www.theinquirer.net/inquirer/news/1030335/leaked-wind...
Leaked source code is not open source dude. Open source is software licensed under terms compatible with these rules: https://opensource.org/osd
I've built the WinXP kernel a few months ago just for nostalgic purposes, here's a VM running the custom kernel with a KDBG hook on NTQSysInfo [1]. The neat thing is that you can debug on the system itself, or via a serial port.
I also know that some people had success merging the /base/ code from the above licensed kernel (but the x86 version) and the leaked WinNT4 code. One even got so far as to manage a recompile of the NT setup, building a custom NT OS from scratch. Though that's violating the WRK and NT license left and right.