True, but it should be possible to create high performance UI controls inside an HTML5 canvas element. With canvas, every browser has hardware accelerated imme

True, but it should be possible to create high performance UI controls inside an HTML5 canvas element. With canvas, every browser has hardware accelerated immediate mode rendering that could be used to create UI toolkits. Looking around the web, there are some attempts to make this happen, but none of them seem to be hugely popular. Last time I looked into this (years ago), a big blocker was that nothing inside a canvas element is visible to accessibility APIs, so UI rendered in a canvas would be invisible to people using assistive technologies like screen readers.