Opera has been busy repositioning itself as a middleware player for the mobile Web recently, but that isn't stopping the company from defending its investment in browser technology. The company has filed a 20 million Kronor ($3.4 million) lawsuit against a former employee and consultant, claiming that he stole company secrets and incorporated them into a mobile browser for Mozilla.

According to a report by Norwegian IT site Digi.no, Opera has filed suit against Trond Werner Hansen, a Norwegian musician and designer who worked for Opera from 1999 to 2006 as a user interface designer and developer before leaving to pursue his music career. Hansen also worked for Opera as an outside consultant from 2009 to 2010. Last year, Hansen was involved with the development of the Mozilla prototype "Junior" browser for Apple iOS. Hansen and Alex Limi—former Firefox UI head and now manager of Mozilla's product design strategy—demonstrated the browser prototype in a video on Air Mozilla last June. Hansen said in the video, "I spent almost seven years trying to simplify Opera and didn't really succeed. Simplification of something that already exists is really hard. That's way beyond product design issues—it's company issues. I feel like we failed in making something really easy."

Limi credited Hansen with the invention of a number of Mozilla UI features, including the browser search—"the source of all our revenue," Limi said—and the "speed dial" feature that allows users to pick frequently visited pages from a new browser tab. "Pretty much everything he's invented, they're now in all browsers," Limi continued.

But now Opera claims that some of the bits of interface magic that Hansen added to Junior contributed to Mozilla were things Opera paid him to develop—features that had not yet been implemented in Opera. So far, Opera is limiting its suit to Hansen himself, who is an independent consultant paid by Mozilla for his product design work. But if the suit is successful, it could potentially pose problems for Mozilla as well, given Hansen's level of involvement with both "Junior" and the Firefox browser.

Update: In a post to his own Tumblr blog, Hansen says he believes Opera's lawsuit is centered on the "Search Tabs" function of Firefox that was demonstrated in the video alongside "Junior." Hansen claims the feature was originally a concept he developed for an open-source browser of his own he started working on after leaving Opera, which he called "GB"—a browser for which the revenue from searches would be donated to "green" causes. "In the summer of 2008, Opera’s founder and CEO at the time, Jon von Tetzchner reaches out and asks if I want to contribute more to Opera," Hansen wrote. "I tell him about GB and propose that we could develop GB as a rebooted and simplified Opera browser. He is very interested, but when we start to talk business, and I tell him that I want no salary and no shares, but 1% of the search revenue as compensation, he says that’s not possible. So there is no deal. In fact, there is never any kind of deal or transfer of ownership of GB concepts to Opera." A year later, Opera brought him on as a consultant; some of the design proposals he made during that period were based on his ideas for GB, he claims.

Most of the development work Hansen was involved with never came to fruition, and his contract was terminated in 2010. "I inform the new CEO at the time, Lars Boilesen," Hansen recounts, "that I will most likely pursue to contribute to an open source project like the Mozilla Firefox browser instead, since I think many of my original GB ideas and the direction I wanted to take the browser still has value, and I would like to see the ideas put into code. In a meeting with Lars, he says he understands that, and my intentions are also made clear in an email to him, but he never replies to that email." However, when Mozilla demonstrated Search Tabs in the video he appeared in last year, "Opera claims that it proves that I must have told Mozilla trade secrets causing them damages of 20 million NOK. ($3.4 million). I strongly disagree with their position and I believe I have been wrongly accused, and that I can prove my case."