Microsoft never tried to rewrite Windows in C# during the Vista project. I know this because I worked on Vista and my team wrote code in C++.
Vista did include some new C# APIs and Frameworks. The best ones were Windows Presentation Foundation and PowerShell (it uses a lot of .NET technologies).
Vista took a long time for a lot of reasons. I do not know all of them but my observation was there were a few basic problems:
1. Teams were allowed to check in buggy code. This led Vista to be unstable while it was being developed. Note the Kernel code was usually very good. The shell was frequently difficult to use because of the bugs and because of poor performance.
Note that when it shipped, it worked much better than it did during development. I remember being shocked at how well it worked. I also remember going back to Windows XP and realizing I actually liked Vista better (it had a better user interface, and I liked the improved Windows Update app).
2. Very poor project management. Basically, no one knew what needed to be done or how long it would take.
3. A lot of overly ambitious projects and features. Some teams really tried to do revolutionary things. Sometimes they succeeded (The Windows Display Driver Model is an example of this). Often, they failed (Media Foundation is a great example of a mediocre API which came out of Vista).
4. Some teams took dependencies on immature APIs or frameworks. The problem was the framework and the applications using it were being developed at the same time. This led to a lot of reworked because applications kept on having to be updated because their dependencies changed or were cancelled.
5. Poor leadership - Will Poole led the Window Client team (AKA the desktop version of Windows). Wille Poole previously led the Windows Media player team. My impression was he valued political skill, politics and empire building over competence and technical excellence.
After Windows Vista shipped, he was "promoted" to working on Windows for Emerging Markets. After that, he "managed" his administrative assistant. He then "retired".
I am sure I missed a lot of things and I certainly do not know everything because I worked on a small part of a huge project. Windows had thousands of software engineers, program managers, testers and managers and they worked on a lot of different things.
It's funny how you can tell who's garbage and who was kickass at Microsoft just based on what they're doing nowadays.
Dave Plummer from Dave's Garage channel on YouTube is a great example of this. Sure, just creating Task Manager alone would get you on the books for being a kickass programmer, but everything else he did, and the fun YouTube stuff he's doing now, you can tell he was really a force behind the scenes in the early days.
You are correct. It was part of the .NET Framework, and it did work on Windows XP. The team which created it was part of the Windows organization and I believe it required changes to Windows to get it to work or run fast. I suspect this is why it has not been ported to Linux like the rest of .NET Core / .NET 7.x .
Vista did include some new C# APIs and Frameworks. The best ones were Windows Presentation Foundation and PowerShell (it uses a lot of .NET technologies).
Vista took a long time for a lot of reasons. I do not know all of them but my observation was there were a few basic problems:
1. Teams were allowed to check in buggy code. This led Vista to be unstable while it was being developed. Note the Kernel code was usually very good. The shell was frequently difficult to use because of the bugs and because of poor performance.
Note that when it shipped, it worked much better than it did during development. I remember being shocked at how well it worked. I also remember going back to Windows XP and realizing I actually liked Vista better (it had a better user interface, and I liked the improved Windows Update app).
2. Very poor project management. Basically, no one knew what needed to be done or how long it would take.
3. A lot of overly ambitious projects and features. Some teams really tried to do revolutionary things. Sometimes they succeeded (The Windows Display Driver Model is an example of this). Often, they failed (Media Foundation is a great example of a mediocre API which came out of Vista).
4. Some teams took dependencies on immature APIs or frameworks. The problem was the framework and the applications using it were being developed at the same time. This led to a lot of reworked because applications kept on having to be updated because their dependencies changed or were cancelled.
5. Poor leadership - Will Poole led the Window Client team (AKA the desktop version of Windows). Wille Poole previously led the Windows Media player team. My impression was he valued political skill, politics and empire building over competence and technical excellence.
After Windows Vista shipped, he was "promoted" to working on Windows for Emerging Markets. After that, he "managed" his administrative assistant. He then "retired".
I am sure I missed a lot of things and I certainly do not know everything because I worked on a small part of a huge project. Windows had thousands of software engineers, program managers, testers and managers and they worked on a lot of different things.