title: CoreAnimation warning deleted thread with uncommitted CATransaction
body: <p>I am having issues with the following warning:</p>
  
  <p>CoreAnimation: warning, deleted thread with uncommitted CATransaction; set CA_DEBUG_TRANSACTIONS=1 in environment to log backtraces.</p>
  
  <p>I am using an NSOperation object to perform some calculations, once complete it sends a message back to the AppDelegate that then hides a progress bar and unhides some buttons.  If I comment out the message back to the AppDelegate the warning goes away but the progress bar obviously remains visible and animated.</p>
  
  <p>I am using xCode 4.4.1 and OSX 10.8.1, however, when I compile and run the code using the same version of xCode on OSX 10.7.4 I do not get the warning and the code runs as expected.</p>
  
  <p>Setting the CA_DEBUG_TRANSACTIONS=1 environment variable shows the backtrace as coming from an NSControl setEnabled message in the AppDelegate.</p>
  
  <p>The answer is probably staring me in the face but maybe I've had too much coffee!</p>