I only dabbled with Gtk-rs for a bit, and Rust does not really fit my UI/UX workflows, but I would still suggest as major improvement a better way to being able to reference struct fields from callbacks without the current Option<Rc<>> workarounds.

There are already some projects that let you do that, consider Relm for example: https://github.com/antoyo/relm/blob/master/examples/http/src...

Is Qt with Rust usable already, or it's still very experimental?

I don't have personal experience, but my understanding is that GTK is much easier since it's in C; QT makes use of some C++ features like inheritance that don't have a direct analogue in Rust that makes it hard. I've heard of several people doing things, but am not sure there's a particular go-to amazing solution at the moment.

The last time I looked into it, there was this project: https://phabricator.kde.org/source/rust-qt-binding-generator...

But it was in the prototype stage then.