Anybody here remembers #sonique ? It was a crazy audio player from #winamp 's epoch that allowed totally crazy UI shapes.
https://en.m.wikipedia.org/wiki/Sonique_(media_player)
This post contains a few that show how skin (theme) makers could completely redo the whole interface:
https://www.reddit.com/r/FrutigerAero/comments/18js4ss/my_fav_sonique_skins_that_i_think_fit_this/