Google Web Toolkit 2.5 Final has been released. It features new optimizations but its two major enhancements, Super Dev Mode and the Elemental Library both have the status of "experimental".

When the GoogleWeb Toolkit 2.5 RC1 was released at the end of June it was anticipated that the final version would follow in less than a month. In fact it has taken four months. Whether this is in any way connected to the fact that GWT is now under the control of a steering committee rather than being fully Google-controlled isn't clear but there have only been minor changes, and bug fixes since the original release candidate.

One highlight of GWT 2.5 is the experimental Super Dev Mode, which replaces the current Development mode. It requires no browser plugins, making it easier to support additional browsers including those on mobile devices. It also introduces a debugger to inspect the running GWT application.

Another is the new (experimental) Elemental library is designed to provide "fast, lightweight and 'to the metal' web programming" for developers who are familiar with browsers' JavaScript APIs.

GWT 2.5 includes new optimizations that produce a 20% code size reduction and a 39% reduction in the initial download size of its Showcase application. The integration of Google's Closure Compiler as an optional backend is one optimization feature. Another improvement is to the Code Splitter which  now has the ability to automatically partition deferred code that is specified by GWT.runAsync() calls:

GWT 2.5 also has a new accessibility library that covers the  W3C Aria standard, making it easier to correctly set ARIA roles, states, and properties on DOM elements.

Extension to UiBinder have been added to support Cell rendering and event handling and IsRenderable / RenderablePanel types have been introduced, which can significantly improve rendering time and reduce the latency of complex UiBinder UIs.