[perlclutcher]

I don't think primitive layout is necessarily a limitation of the immediate mode GUI paradigm. It just requires layout to be deferred until the end of the frame. And of course to do that performantly, you'd likely need some caching between frames.

But here's the kicker: egui already does cache things between frames—for accessibility support, it already builds a full retained widget tree! From there it's not a huge jump to cache layout too. I really wish someone would experiment with this idea. Maybe Gio will be the ones to do it.