title: How do I get an event in Raphael's paper coordinates
body: <p>I would like to get the coordinates of a mouse event in Raphael's paper coordinates.  I would like those to be accurate even when I have used setViewBox.</p>
  
  <p>Please see <a href="http://jsfiddle.net/CEnBN/" rel="nofollow">http://jsfiddle.net/CEnBN/</a></p>
  
  <p>The following creates a 10x10 green box and then zooms way in - with the center of that box at the view's origin.</p>
  
  <pre><code>var paper = Raphael(10, 50, 320, 200);
  
  var rect = paper.rect(0, 0, 10, 10);
  rect.attr('fill', 'green');
  
  rect.mousedown(function (event, a, b) {
      $('#here').text([a, b]);
      console.log(event);
  });
  
  paper.setViewBox(5, 5, 10, 10);
  </code></pre>
  
  <p>I would like to receive click coordinates that reflect their position in the box.  ie. they should range from ([5-10], [5-10]).</p>
  
  <hr>
  
  <p>Note: much later, and I have migrated to D3.js - which has generally made me a lot happier.</p>