it seems like the canvas is a highly mutable thing that isn't save to keep a reference to

for some reason I thought that humbleui wasn't meant to be immediate mode, but it seems like the state of the canvas needs to be re-built each re-render. there's not an engine for diffing and figuring out what exactly needs to change in a declarative way

Like dirty regions? No, I don’t think it makes sense in modern computers. It’s way faster to re-render everything from scratch

maybe a stupid question: is there a difference between re-rendering everything from scratch, and "immediate mode" rendering?

depends on what you mean. Immediate mode UIs usually recreate whole components tree each frame. Immediate rendering is, I guess, rendering all from scratch?

yeah I suppose that makes sense. my brain is broken by browser UIs, I'm trying to learn everything else now

does ski(j)a then take care of figuring out how to draw all this stuff using the GPU?

Yes