Will give a brief reply to what was covered on discord about this...
The idea which is ultimately the relatively simpler way to get a different style of skin engine implemented is going down the VLC/fb2k approach of just not bothering with skinning & using the native OS handling (like the winamp/wacup preferences window does normally) to leverage all that comes from that.
How that native ui should end up being done I'm still uncertain as it can either go the multi-window or single-ui approach but I'm delaying doing work on this for the time being until more of the core handling has been swapped over to wacup code instead of winamp code so it's simpler to just get things working (hopefully, heh).
-dro