The first of these three, 4. 1, was unveiled at Google's I/O developer conference in June 2012, focusing on performance improvements designed to give the operating system a smoother and more responsive feel, improvements to the notification system allowing for "expandable" notifications with action buttons, and other internal changes. Two more releases were made under the Jelly Bean name in October 2012 and July 2013 respectively, including 4. 2—which included further optimizations, multi-user support for tablets, lock screen widgets, quick settings, and screen savers, and 4. 3—contained further improvements and updates to the underlying Android platform.