- the invisible play queue only supports: "Add, replace and play" and is called simply "Play"
- when play from library or from visible queue, the invisible queue is cleared and new item or items are added to the insvisible play queue.
- folders from library can be added to the invisible queue or audio streams.
- adding to the invisible queue is simply called "Play" and is default behavior within all libraries.
- in essence the invisible play queue is always temporary and is reset on each user play action.
- All current features still remain the same.
I think this would hugely simplify the user experience. It makes it possible to briefly listen to music in your libraries and add items to the visible queue when it's interesting enough to add it to an actual play list.