Web site: http://qooxdoo.org/
Qooxdoo is a rich-application framework with a focus on AJAX-powered widgets. It has a large set of core features, including browser detection, event management, drag-and-drop support, a cookie API, and AJAX communications. The focus of the project is on API layout and widgets; the API layout provides an experience similar to using standard graphical APIs, such as Swing in Java. Widgets include menus, toolbars, combo boxes, and windows. Qooxdoo is extremely large, so it won't be a good choice for mixing and matching with other solutions.