Aside: the Windows OneCore and Shell Experience and C-Shell refactoring efforts have done a lot of work moving File Explorer into its own application finally divorced from a lot of the rest of the GUI. You can see it in Task Manager in 10 versus previous, esp. XP: fewer miscellaneous Explorer.exe processes and more fun new components like Windows Shell Experience Host. (Hard-crashing Explorer.exe is a lot less devastating to overall the stability of Windows 10 than it was back in XP [or 95].)

So we seem to be a lot closer today to a world where File Explorer is just another app, and maybe even considerable for open source development, than you may imagine.

I hadn't heard about CShell. Thanks for posting!

Yeah, it's an interesting topic that Microsoft for multiple reasons is keeping mostly behind the curtain. I like following C-Shell rumors, as a Windows mobile fan (rumors are that it was hoped C-Shell would have been a lot faster to build and might have kept Windows 10 on mobile form factors "alive" longer), and also because it sounds like a lot of cool effort that will probably be underappreciated when it actually finishes.

Seeing the announcement about WinFile + Calc got me wondering about MS/Windows File Explorer.

Would you mind expanding on what you don't think MS could open source the File Explorer?