Here is an error reported when Guvnor 6.x is deployed in Tomcat 7.x and accessed from Google Chrome on MacOS :
ERROR: Possible problem with your *.gwt.xml module file.
The compile time user.agent value (gecko1_8) does not match the runtime user.agent value (safari). Expect more errors
Regards,
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Charles Moulliard
Apache Committer / Sr. Enterprise Architect (RedHat)