Drag-n-drop-forms-with-extjs is a project mainly written in JavaScript, it's free.
Simple proof of concept how we can make UI visual maker tool with ExtJS library
Simple Drag'n'Drop Project to show how we can make UI visual maker tool with ExtJS library.
It was a proof of concept code for one of my clients.
You can see how it works here: http://vimeo.com/10244667