How can I make a nautilus-like sidebar using mono gtk#

Question

I have been looking for weeks for a way to do this:

I am working on a music player, and would like something like this:

 Library           >
   Music          (6)
   Videos         (2)
 Playlists         >
   new playlist...

And so on. I am using mono and gtk#. I can't find a tutorial or anything, if someone could help me find one or give me an example that would be nice. Thanks!