rust-objc VS Examples_Cocoa

If you find dealing with the Obj-C bindings a bit daunting (I would), I'd recommend you use the objc crate. That will like you dive into the details of creating and updating Mac windows without having to figure out how to call Objective C from Rust.

There is https://github.com/SSheldon/rust-objc which is abandoned.

On macOS, per-window capture is actually exceedingly easy and officially supported by Apple, either including window shadows or not. I'm not aware of any crate for doing it cross-platform, but the way to do it on macOS is documented all over the Internet and the bindings you need are in the objc and core-graphics crates.

That looks like Objective C, not C. You can call Objective C methods from Rust via the objc crate.

Here is a minimal Hello World Objective C program. You'll need to figure out how declare the needed Objective C interfaces and how to call them from Rust. The C ABI function objc_msgSend will get you part of the way there.

So, the problem I run into is finding resources for learning the GNUstep api. Not to criticize, but when I search many of the links I click on are dead, and when I do find a live one, it seldom gives me much more than a list of methods. I finally found this repo (https://github.com/gammasoft71/Examples_Cocoa) which has given me a lot of help.