Forgive me if there is already an issue for this. I gave it a quick search before opening this.

So, in the long term, after more core OS functionality has been covered, I think it would make sense to have some sort of API for creating and manipulating windows, so that WASI can be useful for user-facing applications. This would only cover the windows themselves, not widgets inside of them, as that's something that can easily be done at a higher level by something like GTK or Qt, so this wouldn't be a colossal project on the level of Swing. At the very most, this API would offer GDI-like drawing, but perhaps even that would be better left out in favour of a more general graphics API à la #53.