title: 3 or more *consecutive* layout passes to prepare to be shown. Error
body: <p>When I open an NSPopover I am getting the following error:   </p>
  
  <pre><code>WARNING: &lt;NSPopover: 0x618000120780&gt; needed 3 or more *consecutive* layout
  passes to prepare to be shown. Verify that nothing in your view hierarchy
  is aggressively dirtying layout during layout, as this will likely
  cause problems elsewhere.
  </code></pre>
  
  <p>This has only just started appearing in a recent build and I can not find what is causing it.  I have removed all prep code before the popover is shown so it basically calls:</p>
  
  <pre><code>- (IBAction)addClicked:(id)sender {
  
  [[self addPopover] showRelativeToRect:[sender bounds] ofView:sender preferredEdge:NSMaxYEdge];
  
  }
  </code></pre>
  
  <p>I have removed all constraints from the window in IB too.  So I shouldn't be doing anything during layout that requires a repaint. </p>
  
  <p>Searching the web comes up with very little info, what I could find anyway.  My popover is used for a form input so has 4 NSTextFields an NSOutlineView and an NSImage.  It also creates a hidden WebView which is not visible to the user and used for server processing.</p>
  
  <p>OSX 10.7+</p>
  
  <p>Any ideas?
  Thanks
  Geoff</p>