title: Disable NSToolbar customisation via window's toolbar button?
body: <p>I am looking to disable the Command + Click combination on a toolbar button (located top-right) in a Cocoa window. I would still like to let the user show and hide the toolbar, but I do not want them to be able to select a different display mode (e.g. small icons, no icons, etc).</p>
  
  <p>Has anyone found a way to do this? Thanks in advance.</p>