According to a new rumor, Samsung is developing a smartphone with a vertically rollable display that would allow users to switch between two aspect ratios. While brands are exploring wide-screen phones, Samsung could offer the best of both worlds with a device that adapts to different viewing preferences.Well-known tipster Ice Universe claims that the alleged device will let users extend the display from a 16:9 to a 21:9 aspect ratio, effectively switching between a wider screen and a taller form factor.The phone will reportedly feature a sliding mechanism that extends the display...