Microsoft released the source code for the original Windows Fillet Manager that was released about 28 years ago with the Windows 3 operating system. 
Η application originally released in Windows 3.0, it replaced file management through MS-DOS. The code has now been "hacked" and so the ancient application can also run on Windows 10! 
However, the function of the application has not changed, since it allows users to copy, move, delete and search for files, which is what it did about 28 years ago.
Ο Source Code (for those interested) is available on GitHub and is maintained by Microsoft veteran Craig Wittenberg with permission from MIt.
Wittenberg copied the file management code from Windows NT 4, 2007 and maintained it until it finally opened it for the public.
If you want to find out what Windows looked like in today's environment (Windows 10), or if you are one of those who want to remember the application, you can download it from GitHub.
https://github.com/Microsoft/winfile/releases
You have to be a masochist to want to try something like this.
Here File Explorer has weaknesses and can be improved - Think of the obsolete File Manager.