LGTM Nice, one minor nit. As we said offline, it'd be good to get Simon Stewart's take on this.
http://gwt-code-reviews.appspot.com/770801/diff/1/10 File user/src/com/google/gwt/resources/rg/CssResourceGenerator.java (right): http://gwt-code-reviews.appspot.com/770801/diff/1/10#newcode979 user/src/com/google/gwt/resources/rg/CssResourceGenerator.java:979: if (debugInfo instanceof CssDebugInfoImpl) { You just made this harder to customize, no? Why not but an isEnabled() method on the debugInfo interface? Or you could make this an == check against the null object? http://gwt-code-reviews.appspot.com/770801/show -- http://groups.google.com/group/Google-Web-Toolkit-Contributors