I wrote that article about nine years ago, and OpenLaszlo never took over the world the way I hoped it would, but Max Carlson, one of its chief architects, is working on reimplementing the good parts in JavaScript/CoffeeScript, without all the baggage. It's a work in progress and not very well documented, but it embodies some wonderful ideas!

https://github.com/mcarlson/rheses

Oliver Steele, another of OpenLaszlo's architects, has written some great stuff about "Instance First Development", a declarative, prototype and constraint based approach to programming modular components that OpenLaszlo supports.

http://blog.osteele.com/posts/2004/03/classes-and-prototypes

http://c2.com/cgi/wiki?InstanceFirstDevelopment

http://lua-users.org/lists/lua-l/2007-10/msg00379.html

http://www.donhopkins.com/drupal/node/124

http://don.fed.wiki.org/view/prototype-based-programming

https://ssl.weepee.org/lps-5.0.x/docs/developers/introductor...

And of course the granddaddy of all constraint based user interface systems is Ivan Sutherland's Sketchpad:

https://en.wikipedia.org/wiki/Sketchpad