This article is just about acceleration and stacking is not introduced. WebKit's architecture ties together the concepts of stacking and acceleration. A positive effect is that it will be quite easy to support stacking in SVG with this work.
A negative of joining the concepts of stacking and acceleration is that it is difficult to get acceleration without introducing paint order bugs where the accelerated content starts painting above non-accelerated content.
A negative of joining the concepts of stacking and acceleration is that it is difficult to get acceleration without introducing paint order bugs where the accelerated content starts painting above non-accelerated content.