I work with applications that generate windows and manage their lifetimes independently of whatever is inside the window. afaict, most web/mobile UI frameworks

I work with applications that generate windows and manage their lifetimes independently of whatever is inside the window. afaict, most web/mobile UI frameworks assume they're the only thing in the universe, whereas on desktop there's a complex application managing zero or more rendering surfaces and portions of the code only know about the one that they're supposed to target. It's a hairier problem than you'd expect it to be. I'm not an expert but my understanding is that it's tricky to deal with the event loops when you're not the master of your domain, at least in a platform agnostic way. The workaround is usually to spawn multiple processes, but then the management of app state has to have an IPC layer underneath the internal APIs and there needs to be a master daemon running somewhere. In keeping with front page posts, the plugin API for Apple's Logic Pro (audio units) is an example of that. You are handed an NSView* and need to render on it, but you don't create it.