Just an fyi that over in the Apache Isis  community (the first cousin to NO MVC, of course) there's been some work done to integrate Isis with a viewer based on DHTMLX 
There's a blog where you can read more , and there's a running example up on GAE .
The guys who did this (Mylaensys) aren't Isis committers, instead have developed the viewer as a spike, but I think they are keen to take it through to production.
What's notable about this viewer is that it supports the NO View language DSL .
One downside is that DHTMLX is GPL licensed, so there's no way that this could ever part of the NO MVC codebase (nor Apache Isis either, for that matter).
Anyway, do check it out. Any feedback on this thread I'll send back to Mylaensys.