DrRacket seems to have doing the thing where they implement of a bunch of GUI stuff from scratch ...
The GUIs actually use the underlying native GUIs thanks to the dynamic FFI.
The goal is to have a cross platform GUI. Your program runs on macOS, Linux and Windows without any problems.
But if there is some gui feature, that is only available on one platform, you won't find it in the builtin gui libraries. However, you can always add platform specific functionality yourself.
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The GUIs actually use the underlying native GUIs thanks to the dynamic FFI. The goal is to have a cross platform GUI. Your program runs on macOS, Linux and Windows without any problems.
But if there is some gui feature, that is only available on one platform, you won't find it in the builtin gui libraries. However, you can always add platform specific functionality yourself.
I can't attest to the implementation. I can only attest to the jank.