This is not a mockup, this is a working Winamp skin, you can try it right now!
You don't have Winamp anymore? Install it and have a glimpse of nostalgia with a modernized shine. All links at the bottom.
Latest Winamp from Nullsoft (v5.666, from 2013) is officially available here.
This skin can be downloaded at DeviantArt.
. . .
Alternatively, Winamp keeps on living through WACUP, an independent project aimed to improve what's already good and bring to life long requested features, among new plugins and better OS implementation. Check it out here.
