Author here, that would make sense, except it doesn't appear to be doing that. I also don't see anything in the docs suggesting that it would. My test app takes

Author here, that would make sense, except it doesn't appear to be doing that. I also don't see anything in the docs suggesting that it would. My test app takes 1ms to render yet, and the callback returns within 100us, but it's consistently calling me 7ms before vsync. I'm also not actually working on anything that uses this right now, I was just curious. I'm just warning about the dangers if you have inconsistent rendering time.