Please do not use this patch. The leak is fixed in trunk by http://code.google.com/p/google-web-toolkit/source/detail?r=10201 and http://code.google.com/p/google-web-toolkit/source/detail?r=10344
http://gwt-code-reviews.appspot.com/1401802/ -- http://groups.google.com/group/Google-Web-Toolkit-Contributors