"Jobs spent part of every day for six months helping to refine the display. "It was the most complex fun I've ever had," he recalled. "It was like being the one evolving the variations on 'Sgt. Pepper.' " A lot of features that seem simple now were the result of creative brainstorms. For example, the team worried about how to prevent the device from playing music or making a call accidentally when it was jangling in your pocket. Jobs was congenitally averse to having on-off switches, which he deemed "inelegant." The solution was "Swipe to Open," the simple and fun on-screen slider that activated the device when it had gone dormant. Another breakthrough was the sensor that figured out when you put the phone to your ear, so that your lobes didn't accidentally activate some function. And of course the icons came in his favorite shape, the primitive he made Bill Atkinson design into the software of the first Macintosh: rounded rectangles. In session after session, with Jobs immersed in every detail, the team members figured out ways to simplify what other phones made complicated. They added a big bar to guide you in putting calls on hold or making conference calls, found easy ways to navigate through email, and created icons you could scroll through horizontally to get to different apps--all of which were easier because they could be used visually on the screen rather than by using a keyboard built into the hardware."