[treyd]

> Literally just not being able to easily and efficiently express interior mutability completely changes how you design both code and APIs.

The issue is that fundamentally interior mutability is hard to reason about. It requires a lot more temporal reasoning to make sense of and ensure the safety of. Leaning into the type system Rust has does make interior mutability harder when you have "temporally based" safety arguments. It's a lot easier to reason about correctness in the model Rust uses.

Have you looked at the godot-rust bindings? They've gone very far to make the Godot object system work well going between C++ Godot code and Rust. I would love to see that model adapted to Gtk.