Comment by leecommamichael

> What about when you're embedding your GUI into an existing application? or for use on an already taxed system?

You should check out the gamedev scene. It's soft real-time, and yet dearIMGUI is the choice for tooling. Immediate-mode is an API-design, not the implementation details. All Immediate-mode GUIs retain data some data, and for that reason they each have their own APIs for retaining data in various capacities. Usually something really simple like hashing and component-local state.

> This works for simple apps, utilities, and demos/mvps. Not great for actual applications.

Respectfully, I don't think you're informed on this. Probably the most responsive debugger out there is RAD Debugger and it's built with an IMGUI.