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 smartphones (what you see above) as well as a not-entirely-practical design with keys on opposite sides of a display, much like a single-screen LG Doubleplay. We're not expecting BlackBerry to ship related products anytime soon when the Q10 represents its immediate future in hardware keyboards, but it's tough to rule out the ideas altogether when they could slim keyboarded phones without losing that coveted stealthiness. They might stand a better chance of reaching the market than some of BlackBerry's more outlandish experiments.