Full-screen designs are a thing now and every smartphone maker has its own take on the matter. Some prefer pop-up cameras, others are still stuck with notches (ahem, Apple and Huawei) while yet others are just slapping a second screen on the back of their devices. After the vivo NEX Dual Display, here comes the nubia Z20. The nubia Z20 has a unique twist to its secondary screen design. When the screen isn't on, the back looks like a standard curved glass panel with a flashy gradient paint job but once you turn on the secondary screen, the better part of the back lights up. The...