Relations, scripting features (reflection and no high level
OOP api or high level compile time API), and various other features, making it suitable for a high scale UGC game.

I don’t know if immediate mode GUI will be performant enough in the end but I have a feeling it will be more than good enough. If not, I can always provide other options to users of my UGC game or engine.

ImGUI also has a lot of plugins / UI components that the community has made since it’s a popular library that’s been around for a while. Which also is a benefit, stability, vs newer experimental Rust libs, and it’s even integrated into large engines like Unity. I also use C libs already.

I haven’t looked deeply into those UI libs but I have a lot of practical reasons for choosing ImGUI. It’s easy to integrate with ECS, it’s portable because it’s written in C (cimgui at least), I have previous UI code for my game that’s written in ImGUI I can reference for the new version…