well, I am thinking about an OS based on managed code.
Look up Singularity or Cosmos. But be aware that managed code != no security vulnerabilities (look at the huge raft of security issues Java or Android apps has had for instance)
Really strong siloing of apps so no such thing as a virus.
PHP is entirely managed and is "isolated", and yet PHP websites get hacked all the time, leading to the customer data being stolen.
Much better problem determination features, where I can freeze the system and examine in depth what a process is doing.
WinDbg does this already for Windows
My superior OS would be well documented with a lot of sample code for every interface.
Better documented than MSDN? Really!?
I am sure W8 is better, but W7 is very slow to start. You have to do better at that.
They did. Win8.
The windows shell, at least from a programmer's perspective could be a lot better.
Copy/paste between apps is so useful, you have to be able to do a lot more with that.
Copy paste between apps is already pretty powerful via the OLE clipboard. What would you like it to do that you can't get it to do currently?
IE could be much better - save everything I browse to, enable me to skip advertisements in videos. Favorites are nice, but do you really need superior hierarchical organizational skills to know how to store a favorite so you can find it at a later time?
That's not programming language specific. That's a design/UX issue.