title: In Swift 2, what is the proper way to disable a NSMenuItem?
body: <p>There is a public enabled property but setting it to false has no effect.</p>
  
  <pre><code>startItem.enabled = false
  </code></pre>
  
  <p>My current solution is to set action's Selector to empty string.</p>
  
  <pre><code>var startItem = NSMenuItem(title: "Start", action: Selector(""), keyEquivalent: "")
  </code></pre>
  
  <p>This feels unintuitive as to why you can set enabled to false but not have an effect. </p>