title: Create a simple button in Unity3D 2D mode
body: <p>I'm working on a 2D game in Unity 3D, v4.5. I have added some sprites to the Hierarchy. How do I add a button to the hierarchy? I already have a designated button.png that should display as the button. Should I turn a sprite into a button?</p>
  
  <p>What I tried so far:</p>
  
  <ul>
  <li><p>Someone noted GUI.Button, but</p>
  
  <p>1: It has to be done in code - I assume we can add buttons to the game UI inside Unity GUI (??)</p>
  
  <p>2: Even using GUI.Button from script, that class adds a border around the specified texture. I also haven't figured out how to use the existing image and size (width/height) of the sprite as the texture that is sent to GUI.Button.</p></li>
  </ul>