go-fltk does build and run on Windows, pretty well actually.

For a native toolkit, I was impressed to see FLTK supports Ctrl-+ and Ctrl+- to zoom the entire application like a browser. And https://github.com/fltk-rs/fltk-theme?tab=readme-ov-file#wid... really improved my impression of how "native" FLTK can be made to look.

On a related note, I discovered GoVCL https://z-kit.cc/en/ recently and am interested to try it out.