I'm always interested in learning about GUI toolkits that have accessibility support. What level of accessibility support does yours have? e.g. does it implement platform accessibility APIs, and if so, on which platforms? Is your library open source? If not, can I see it in action in any commercially available product? Thanks.
The way it works is that it has an immediate mode API (see https://github.com/sq/Libraries/blob/0ca01d949e3df5fabb1440d... for a simple example of the API) and then under the hood it uses a lightweight retained-mode graph, which means that when it's more convenient you can just write more traditional classes and components. In practice most of the UI I've written for my main project is a mix of both models, like for example an editor popup window uses IMGUI-style API while the items in a virtual listbox are represented by a small custom component.
It does have a full imgui-style layout engine under the hood instead of doing retained-mode layout, so it's able to fully re-generate layout from scratch every frame, and to minimize page tearing there is a system where components can request a second relayout pass (typically used for things like text autosize).
Here's a more complex mixed-mode example from one of my development tools: https://gist.github.com/kg/6a6ba42d5019b546858a2b18751de019
Almost all of the on-screen elements in this footage are either immediate-mode or retained-mode UI using the library: https://www.youtube.com/watch?v=ey3FtFWxbhA
This is not to diminish the quality work that went into the library, but I passed over it for those and other reasons. I used nuklear for a bit since its typography was extensible but in the end it was too hard to overcome its other issues, so I use a custom mixed immediate/retained library now with rich text and accessibility support.