title: Unity 4.6 (new UI): Button click with complex image
body: <p>I have a Button (Canvas>Panel>Button) with a complex image (is not square), the issue here is that I want it to execute the on click event when i click on the IMAGE (excluding parts of the image with no opacity) but since the new UI doesn't work with colliders I can't achieve the same click behaviour that could be achieved with a polygon collider, and its feels completely wrong to click outside the button (image) where the alpha is cero (0) and still execute the click events..</p>
  
  <p>I hope my problem is clear enough and someone can help me, thanks in advance. </p>