It’s a shame that out of all of the Xperia handsets launched by Sony Mobile this year, only one had an illuminated transparent bar that could light up in various colours. It is one of the most endearing features of the Xperia U and devs have been able to hack it in various ways. Another such app is U-Disco, which brings different coloured light patterns to the transparent bar.
The app requires root access and works with both the Sony Xperia U and Xperia P (sans any colour). A free version is on the Play Store along with a Pro version for £1.00. Extra features found on the Pro version include more colours, the ability to edit blink patterns and allows the app to run in the background. Check out the video below showing the app in action.