In some CyanogenMod-based ROMs, holding volume up or volume down while the screen is off, and music is playing, will skip to the next or previous song. This is very useful if my phone is in my pocket and I want to go to the next song. But right now I'm using CivZ_Multi_Flex (http://forum.xda-developers.com/showthread.php?t=2219353) which is based on stock, and doesn't have that feature. I'm wondering if there's a way to add it, so it behaves just like in CyanogenMod.