title: jquery jrac, how to set center point watching when load
body: <p>I see in document have viewport_content_x, viewport_content_y but I set it seem to not effect. It alway show at position 0,0 . <a href="https://github.com/trepmag/jrac" rel="nofollow">https://github.com/trepmag/jrac</a></p>
  
  <p>Did I config wrong something?</p>
  
  <p>And how to prevent error get wrong value (crop_x,crop_y, crop_width,...) when the drop_box is move out image</p>
  
  <p>Thanks very much :)</p>