I'd love to be shown an example, because I honestly don't believe it is doable, let alone doable easier than just making several different applications.
Non UI code lives in a static/shared lib that gets called from UI code. The non-UI code shouldn’t be coupled to a UI at all, instead reporting progress/completion via callbacks or other notification mechanisms.
If you must run on every platform for whatever reason, there is Rust, C, C# (Xamarin), etc.
That's a valid architecture, but it's not a cross platform UI library that uses fully native looking UI on every platform which is what I'm skeptical of working.
I don't think that fully native-looking UI is a very important thing. Not all of the software has a fully native UI on my computer, and it doesn't matter at all.
I completely agree, but the conversation above was speaking to native UIs being a benefit, and there being alternatives that allow you to "write once run anywhere" with native UIs (which I disagree that this even exists in any usable form)
I'm late, but I think wxWidgets tried this. It was OK, I wrote some stuff with it, but mainly targeted Linux. There were definitely some differences in widgets between platforms, but it looked pretty good for not much effort.
