Opera Software has sued a former designer, claiming that work he did for the company ended up in a project at rival Mozilla, according to Norwegian press reports today. Trond Werner Hansen, who left Opera as a full-time employee in 2006 but later worked for the Norwegian browser maker as a consultant from 2009 to 2010, faces a $3.4 million damage suit filed by his former employer, Dagens Naeringsliv reported Monday.