Comment 31 for bug 671632

For me playlists and crates cover entirely different use cases. So there is no need to treat make folders of them the same.

I think we need a roundup about our requirements.
I will give it a try:

* We will have folders, crates and playlists.
* We have AutoDJ crates
* We should keep in mind that we will also have smart crates in future. (Crates filled automatically by a rule)

Question: what is a folder?
* A collection of crates, playlists, smart crates and folders?

Usecase Playlist folders:
* Grouping Playlists: We may have different dinner playlists in a dinner folder.
IMHO it is fine if we treat it exactly like a file system folder containing m3u playlists.
A recursive view is not required. Every Play list has is exactly one time in the folder tree.

Usecase Crate folders:
* Organize the library hierarchically as desired.
A crate should be allowed to be a member of many folders.
I use crates in terms of Tags, a track can be tagged "floorfiller" and "femail vocals" by dropping it into the "floorfiller" and "female vocals" crates. It would be nice to group these tags into folders and see a recursive view of all tracks in the containing crates.
I like to decent to "floorfiller" -> Rock

What is the difference between a Crate folder and a Smart Crate?
A smart crate is a saved library Filter. The filter for a Crate Folder containing "floorfiller" and "femail vocals"
Is crate:floorfiller AND crate:femail vocals"

Is this probably redundant?

What about keeping the flat crate structure but add a smart crates tree instead?