RmlUi VS nuklear

How about https://github.com/mikke89/RmlUi ?

Check out these: https://github.com/ocornut/imgui https://github.com/mikke89/RmlUi

See the release notes here: https://github.com/mikke89/RmlUi/releases/tag/5.0

You're right, it's a fork of libRocket. The original library hasn't seen any development in years, so in a sense RmlUi is a continuation of it too. There's been a lot of changes since then, you can see all of it in the full changelog here.

I haven't actually used either one, but there's HikoGUI (previously known as TTauri) under the Boost license and RmlUI under MIT. Not sure if they're very OS-integrated in the way you want or not.

RmlUI

Nuklear is an alternative Immediate GUI, also written in C.

> And for the right project, especially those where a predefined engine structure does not not fit, it can still be the most productive choice.

Right on. While interning at an oil refinery, I developed an application in LÖVE that processes and displays data from spectrometers. In hindsight it may not have been the wisest choice, but hand rolling all the GUI elements I couldnt force out of the Nuklear[0] bindings for LÖVE gave me a strange sense of satisfaction.

[0]: https://github.com/Immediate-Mode-UI/Nuklear

No, Nuklear has been updated 2 days ago.

I think good option would be nuklear it is a single header lib

For GUI, there are lots, most well-known of course being Dear Imgui, for which people have made auto-generated C bindings. Another mature but a lot simpler option is Nuklear, as others have mentioned. Even more minimalistic (it's just 1KLOC) is microui. There are a lot more, just google "imgui library c".

What about https://github.com/Immediate-Mode-UI/Nuklear ?

Nuklear? They have a number of backends.