We have made a deicsion at this point to only support GWT 2.3+ in our latest release (1.3). The use of the parserStrict() method is part of an ongoing attempt to secure our code against security vulnerabilities such as cross-site scripting attacks. Another is our focus on HTML5. Thus, tracking new features within GWT 2.3 which provide us better support therein is a natural fit.
As our project moves forward, we will make an effort to improve our compatibility profile with various GWT versions.