To see what? Note that the window under it, with its white background, actually has a setTimeout when it repaints: https://github.com/magcius/xplain/blob/gh-p

To see what? Note that the window under it, with its white background, actually has a setTimeout when it repaints: https://github.com/magcius/xplain/blob/gh-pages/src/article-demos/x-basics.js#L183 https://github.com/magcius/xplain/blob/gh-pages/src/article-... Without that, even in a slow JavaScript implementation, you can barely see the white background. As I explain in the article, this is entirely because of memory pressure limits of the 80s. This is what Windows 7 does too. And in a modern environment (compositing manager), windows do get their own backing pixel memory.