Microsoft released Internet Explorer 7 on October 18, 2006. It included tabbed browsing, a search bar, a phishing filter, and improved support for web standards (including full support for PNG)—all features already long familiar to Opera and Firefox users. Microsoft distributed Internet Explorer 7 to genuine Windows users (WGA) as a high-priority update through Windows Update. Typical market share analysis showed only a slow uptake of Internet Explorer 7 and Microsoft decided to drop the requirement for WGA and made Internet Explorer 7 available to all Windows users in October 2007. Throughout the two following years, Microsoft worked on Internet Explorer 8. On December 19, 2007, the company announced that an internal build of that version had passed the Acid2 CSS test in "IE8 standards mode"—the last of the major browsers to do so. Internet Explorer 8 was released on March 19, 2009. New features included accelerators, improved privacy protection, a compatibility mode for pages designed for older browsers, and improved support for various web standards. It was the last version of Internet Explorer to be released for Windows XP. Internet Explorer 8 scored 20/100 in the Acid3 test, which was much worse than all major competitors at the time.