[asveikau]

I was on the Windows team for a few years. I have seen the source code. There is cruft as there will be with any project of its age, but it's not nearly as bad as people say, especially if you can navigate it well. There are some good ideas underneath. COM is generally a good idea. The mental model of message pumps and window procs doesn't really have deep flaws, and lots of UI frameworks on other platforms have the same ideas under the hood. You mention ntdll, it's a shame more of that isn't public, because those APIs are often cleaner than their public equivalents.