When we think of hidden keyboards on our phones, our thoughts usually turn to thick sliders -- notwithstanding the occasional wacky twister. BlackBerry has filed for a pair of patents that would be even subtler by hiding the keys inside of a phone's main body. Looking somewhat like concertinas in practice, the concepts would pivot keys into place as the phone owner pulls out a retractable section to start typing. BlackBerry suggests it could work for both conventional smart
