I don't and never did use much Flash/AS, but wouldn't Haxe be a more logical choice? It is already battle tested and it is a lot more like AS/Flash than Dart? Not sure what experienced Flash devs would think; any here?

Plus, with Haxe and openFL, you will be able to ship native c++ build of your game for free (same code).

If only Haxe could add something more uptodate for multicore concurrency than thread.

What api do you use ? canvas ? webgl ? svg? do you use 1 canvas , or multiple canvas for the object graph ect... How do you handle rich text? do you handle 3D ? filters ? ...

that's the kind of info i'd like to see on the homepage ,HTML5 doesnt mean anything today without the details.

"The Stage class represents the main drawing area and is a wrapper over the HTML5 Canvas element"

Judging by the example source they use canvas, but I dont know dart so cant tell if its one canvas or frame buffers in multiple canvases

For what I see on the Showcase games, they are canvas, but I really hope it supports webgl also, looks like an interesting library.

Perhaps showcase and documents section may answer some of your questions?

Dart w/ StageXL maybe a logical next step for developers stuck with legacy Flash applications (and I think of all Flash application as legacy moving forward).

This looks nice :D