"Macintosh support was our most requested improvement," says Bret Taylor, Google's senior product manager for developer tools.
The toolkit also makes use of Google's expertise in resolving the small differences between Microsoft Explorer, Apple Safari, and open-source Firefox browsers. Browser differences typically plague Ajax programmers as they try to build effective user interactions into their Web applications.
Google supplies a set of user interface components with the toolkit, which it calls widgets. In Release 1.2, the widgets have been enhanced to allow more sophisticated user interfaces. The 1.0 version allowed the creation of a file tree, such as the plus or minus hierarchical files sometimes shown on the left side of a Windows screen. With Release 1.2, such a listing can include check-off boxes, allowing a user to select multiple elements of the tree. Taylor said the latest release also addresses performance issues and fixes bugs found in the previous release. The toolkit is available as a free download.
The key developers of the toolkit, Bruce Johnson and Joel Webber, are working on a book on the toolkit, The Google Web Toolkit, to be published by Addison Wesley later this year. "We hope it will become a desk reference," Taylor says.