Opera had been a long-time small player in the browser wars, known for introducing innovative features such as tabbed browsing and mouse gestures, as well as being lightweight but feature-rich. The software, however, was commercial, which hampered its adoption compared to its free rivals until 2005, when the browser became freeware. On June 20, 2006, Opera Software released Opera 9 including an integrated source viewer, a BitTorrent client implementation, and widgets. It was the first Windows browser to pass the Acid2 test. Opera Mini, a mobile browser, has significant mobile market share. Editions of Opera are also available for the Nintendo DS and the Wii.