Add Status/Bottom Bar to window via Interface Builder/Code

Hi everyone,
I’m really enjoying reading your book, great work =) I’ve managed to setup my storyboard as well as the NSSplitViewController without any problem. Now I was wondering, how I can add a Bottom Bar (see Finder window) in Interface Builder. Is this possible at all or do I have to do the SplitViewController setup programmatically?

As far as I know you have to change some (not sure which) layout constraints and set the following

self.window?.setContentBorderThickness(21, forEdge: NSRectEdge.MinY)

Unfortunately, IB doesn’t let me set the window.contentsView constraints.

Thanks in advance.