Excellent writeup, thanks for posting. I was involved with efforts to achieve similar things in Windows (Direct Composition, etc.). In practice, it was enlightening to debug various apps and frameworks and discover just how long repainting can take and how many edge cases there are around slow apps, hung apps, and so on. Who knows, maybe someone there still has some of the malicious test apps I wrote (using the language of this article, apps which acknowledge the sync request and then take multiple seconds to actually paint, etc., etc.).<p>It's definitely a hard problem space that's basically incompatible with how most GUI apps and frameworks worked from 1985-2015.