Sencha Designer

Sencha Designer is an app that allows you to build desktop and mobile applications. Designer now includes a built-in editor so you can add your own code any time you want.

You can toggle between the design view, which gives you access to Designer visual controls, and code view, where you write your JavaScript. The files are saved to .js files on the file system, so you can use your editor of choice, or the built-in editor in Designer.