title: NSTableview with 2 vertical headers
body: <p>I try to achieve something like this:<img src="https://i.stack.imgur.com/htLaz.png" alt="enter image description here"></p>
  
  <p>I got a view-based NSTableview and i'd like to show the search results in this tableview. But i need to show the search results for web and for the local library search separately.
  So i am wondering how i can get 2 headers vertically aligned in a NSTableview, or is something different used in the shown picture ?</p>
  
  <p>Thanks </p>