With the beginning of widespread HTML5 support and Canvas support, it seems that someone could create a desktop-esque windowing system library for RIAs. Something similar to Qt or WxWidgets. All the required parts seem to be there (runtime language: javascript, pixel drawing: canvas, even vector drawing with SVGs).
This seems to me anyway that it could be a huge leap for the ease of development of RIAs. Forget about classic HTML and styling, and simply create widgets like you would in a desktop application.
I have been searching around on the web for quite a while though and can't find anything that jumps out at me as fitting this description. Am I missing something or is there just nothing like this out there yet?