title: javascript selection/range coordinates
body: <p>I would like to absolute-position a div on either the initial or terminal corner of a text selection, as the user drags their mouse along. Unfortunately, Range only provides the index position, not the x/y coordinates. I think there might be a way to do this with range.insertNode, but only for one side. (This might also help someone position an auto-complete box under a contenteditable.)</p>
  
  <p>How can I get the x/y coordinates of a text selection, or of the text cursor?</p>