The iPhone could one day come with buttons and controls that blend right into the background, effectively making them invisible. Granted to Apple by the U.S. Patent and Trademark Office, a patent dubbed “Disappearing button or slider” describes how various controls on the iPhone and other devices would normally stay hidden and fully appear only when needed. A button would be made of the same material as the housing of the phone, so it would blend in seamlessly. But it could be selectively backlit through small holes to pinpoint its location, or the backlight itself might be activated when you tap the button. The button could also be activated if it senses the motion of your finger or detects heat or sound. A slider control would operate under the same principles, remaining invisible most of the time and popping up only when activated.