Well the code is attached to the first post in this thread. It is based on an old version of Ext though. I personally wouldn't use it for anything other than to get an idea of how someone else went about doing it.
This seems like a wonderful product. However, some of us adhere to the Open Source philosophy and the thought that everyone has rights as described by the Free Software Definition.
In that light, I too am interested in open projects that allows you to build interfaces rather than some commecial product that is steeply priced at $400, making it only feasible for commercial developers that use it on a regular basis rather than the occasional Ext design for non-profit projects.
I am curious if any free alternative has ever been developed for a more modern Ext version. Like Ext 4.
I am not aware of any open source alternatives for 4.x. I love open source software and the philosophy behind it. The issue is that when there are alternatives to proprietary software, they are often incomplete, lower quality, or not maintained. The lack of maintenance is exactly why this project is stuck in a very old version of Ext. I certainly applaud anyone's effort to develop an open source alternative. Most people would rather spend the $400 or just code by hand than spend the massive amount of time to develop an alternative though.
Personally, I would just code by hand for non-profit projects since the framework itself is available under the GPL. A GUI builder is by no means required for developing an Ext application.