Overlaying views & positioning
<p>I have a tab bar view, and another UIView which contains a button, which needs to be visible just above the tab bar.</p>

<p>I have added another view which always sits above the current select tab's view, but can't figure out how to make it sit just above the tab bar <img src="http://img.skitch.com/20090524-jq6ufyiwp6c2uu1x5tkrrsd97m.jpg" alt="Screenshot" /></p>
