title: Setting content edge insets on a UIButton doesn't work as expected
body: <p>I have a UIButton that is set up like this:</p>
  
  <pre><code>UIButton *button = [UIButton buttonWithType:UIButtonTypeSystem];
  button.backgroundColor = [UIColor redColor];
  [self addSubview:button];
  [button setTitle:@"myButton" forState:UIControlStateNormal];
  </code></pre>
  
  <p>The result looks like this (non red colors are background behind the button):</p>
  
  <p><img src="https://i.stack.imgur.com/1p14Q.png" alt="enter image description here"></p>
  
  <p>If I set <code>[button setContentEdgeInsets:UIEdgeInsetsMake(0, 0, 0, 0)]</code> the result looks the same.</p>
  
  <p>If I set <code>[button setContentEdgeInsets:UIEdgeInsetsMake(1, 0, 1, 0)]</code> the result looks like this:</p>
  
  <p><img src="https://i.stack.imgur.com/LToOW.png" alt="enter image description here"></p>
  
  <p>If I set <code>[button setContentEdgeInsets:UIEdgeInsetsMake(-1, 0, -1, 0)]</code> the result looks like this:</p>
  
  <p><img src="https://i.stack.imgur.com/E5NWO.png" alt="enter image description here"></p>
  
  <p>Why does it look like having a positive content inset for top and bottom of 1.0 gives a smaller content inset than 0 (which I understand from the docs is the default)? I am running in Xcode 6 and iOS 7.</p>