"the issue is that the macros for subclassing in gtk4-rs are _really_ verbose and confusing."

I didn't find it that complicated but I've also worked on plenty of GObject code in C. It's mostly a direct equivalent to what the C code would look like. I think part of the problem is that some of the examples are not really structured well, the mod/imp split makes it a lot more confusing than it needs to be. In my opinion you can just skip putting methods on the private struct and only put it on the public one and that also simplifies it a lot.

But Relm should be a step up if you like the declarative style.