Echo Studio

EchoStudio is an Eclipse 3.0-based rapid application development tool capable of creating web-based applications that work and act like rich clients. Building upon the power of the open-source Echo Framework, EchoStudio offers easy-to-use tools that enable developers to design more compelling user interfaces in less time.

The Form Editor enables you to create user interfaces with a simple point-and-click interface. The upper left area of the screen shows the hierarchy of components making up the form, while properties of the selected component may be edited in the region below. The preview pane is automatically updated whenever you make a change and always show exactly what your application will look like on the client web browser.

Come to more detail: http://www.nextapp.com/platform/echo1/echostudio/