This has been said because Ext is a very high level language for Web development. It is almost DSL like versus offering low level functions that you can sprinkle in your code. If you buy into the Ext way then you can build UIs in a very simple manner through JSON. This is all perfectly setup for a design tool, and with Ext Designer, they have it.

Feature Highlights

• Fast prototyping of the look and feel of an application. Ext Designer enables developers and designers to assemble robust layouts by dragging and dropping their components together.
• Fine-tuning without hand coding. Easily change the layout of a specific component, or use the inspector to fine-tune detailed properties.
• User client-side data stores. Ext Designer includes several new ways to incorporate and configure data stores, which can then be bound to components like DataGrids and Trees. Whether your data is in JSON, XML, a simple JavaScript array, or an Ext Direct connection, Ext Designer can help you build a data store for it faster than ever.
• Compatible with other development tools. Once the application design is finished, code can be exported on a component-by-component basis, as either JSON or JavaScript classes. Ext Designer creates tight JavaScript that can be imported into any popular IDE.

Interestingly, the tool is a desktop application versus a Web app like Bespin, CodeMirror, or Ares. Some will be happy with this, as it gets the benefits of a desktop tool…. but I am a fan of where Ares in particular innovates (it lets you easily integrate your desktop files with the cloud…. via a Java apple