title: unlockFocus called too many times
body: <p>I click on a <code>NSButton (openPane</code>l) which is located on the main window of my OS X app to show a <code>NSPanel (myPanel</code>) using the following method:</p>
  
  <pre><code>- (IBAction)openPanel:(id)sender {
      [_myPanel makeKeyAndOrderFront:nil];
  }
  </code></pre>
  
  <p>Everything works as expected except I get the following description in the debug area only the first time I click on the button (openPanel):</p>
  
  <pre><code>"unlockFocus called too many times. Called on NSButton: 0x610000141080."
  </code></pre>
  
  <p>The attributes of the Panel are selected as follows:</p>
  
  <pre><code>Style: Utility Panel, 
  Appearance:Title Bar and Shadow, 
  Controls:  Close, 
  Behaviour: Restorable, 
  Memory: Deferred
  </code></pre>
  
  <p>I have looked through the web but can not find any explanation. Does anyone know why this happens or how to resolve it?</p>