title: using offset on an element inside bootstrap modal returns zero
body: <p>im making an application using html canvas. i tried getting the offset for the canvas using jquery's .offset() method and it was ok. my problem is when i tried putting the canvas on a modal, the offset() returns 0... how do i get the correct offset of the canvas inside a boostrap modal? </p>
  
  <pre><code>canvas = document.getElementById('canvas');
  context = canvas.getContext('2d');
  canvasOffset=$("#canvas").offset();
  offsetX=canvasOffset.left;
  offsetY=canvasOffset.top;
  </code></pre>
  
  <p>canvasOffset returns top and left as zero...</p>