title: Dismissing modal view controller
body: <p>Issue: When dismissing a modal view controller, the header on the presenting view controller is moved up (what looks to be around 20 pixels). </p>
  
  <p>Steps to recreate:
  Create a tab bar controller (T), inside create a navigation controller with (N) a root view controller (A).  </p>
  
  <p>Setup another view controller (B) (this is the view controller to be presented modally)  with a delegate so we can notify the presenting view controller (A) when it should dismiss the modal (B).  </p>
  
  <p>Inside the navigation controller's root view controller(A) create an instance of (B) by instantiating it from the storyboard with it's storyboard id, then present (B) with [self.tabBarController presentViewController:(B) animated:YES complition:nil];. </p>
  
  <p>Have a button on (B) that when pressed triggers the delegate function to notify (A) to dismiss (B) by using [self.tabBarController dismissViewControllerAnimated:YES complition:nil];</p>
  
  <p>So far all works as expected.  However once the modal view controller (B) is dismissed.  The navigation header on (A) is moved up about 20 pixels.  </p>
  
  <p>I cannot figure out why the navigation header is moving up when the modal is dismissed.</p>