title: Finder-like Browser View
body: <p>I have an App that lets the user choose a Browser, or Column View, much like Finder. Since it allows the user to browse a Backup, I'd love to have something like the Finder has in Column view. You select a file, and it shows details about it in the column view, next to the file, like this: 
  <img src="https://i.stack.imgur.com/w2ccc.png" alt="Image"></p>
  
  <p>My application looks like this, when a leaf is selected: 
  <img src="https://i.stack.imgur.com/zAXhZ.png" alt="Image"></p>
  
  <p>Here, you can see how a sort of Preview/Inspector thing might help. I have it all set up in an NSView, but just have no idea how to add that functionality in there. Any help would be greatly appreciated!</p>