Okay. I wrote StrikeDisplay.blogspot.com which does what this is trying to do. I haven't had much time to work on it for awhile, but I try to keep an eye on developments in this area.
I reviewed the code. I think it's a good effort and it's on the right track, as far as developing a seamless parent/child display chain coupled with event chain for the kind of things we take for granted in Flash. It gets some things right; like apparently re-scoping mouse events with target and currentTarget, which is good if you're expecting methods listening for the events to be scoped in some other way than window or document.
The two issues I see with this library are serious deficiencies in performance -- which could be improved upon, of course, although some of the architecture requiring redraws on every frame is just inefficient as has been pointed out -- and also issues with the way bounding boxes are implemented and how collision/rollover checks are implemented. First of all, it useless to have rollovers always based on rectangles, especially if there aren't careful z-ordering methods. Secondly, having an inner and outer bounding box is a very slow method for traversing the redraws and checking events (so are a lot of other bb methods in canvas. everything's slower in canvas than in Flash). The closer to native browser bone you can cut on this, the better; my solution to click collision checks in StrikeDisplay was to implement a hidden canvas on top of the visible one, that duplicated everything drawn in white, everything else in black, and check the pixel color value of that canvas when the mouse clicked or went over anything inside a bounding box. This turned out to be a hell of a lot faster.
I'm happy to see these kinds of libs come out, because if we do have to give up all the comforts of flash or unity or javafx to develop in this nightmare DOM with nothing but a raw canvas, the sooner we can bridge the gap between visual-oriented coders and everyone else, the better for everybody. This one needs work, but I'd rather see something along these lines than most of the other stuff I've seen come out that's DOM-centric rather than based on a display chain.