I don't think Win32 UI API is terrible. It's basically message passing object orientation before its time. The API idioms are clumsy to code against, but OTOH

I don't think Win32 UI API is terrible. It's basically message passing object orientation before its time. The API idioms are clumsy to code against, but OTOH it's much more viable to avoid linking libc into your app, whereas in Unix land, the only portable API is defined largely in terms of a C worldview. And some things are just leagues better, like signals vs structured exception handling.