title: Rotate a group of objects using KineticJS
body: <p>I have a group of objects [ circle and some lines] in a group. i wish to rotate the entire group by an angle[say 90] where the rotation being on the center of the 
  circle. Yet when rotating the group it doesn't rotate on the offset it set to be the center of the circle. </p>
  
  <p>Any help or comments will be appreciated thanks!.</p>
  
  <p>@JohnWiseman as requested here is my code.</p>
  
  <pre><code>var x = petridishGroup.getChildren()[0].getX();
  var y = petridishGroup.getChildren()[0].getY();
  
  var offX = x + petridishGroup.getChildren()[0].getRadius().x;
  var offY = y + petridishGroup.getChildren()[0].getRadius().y;
  
  petridishGroup.setOffset(offX, offY);
  petridishGroup.setRotation(45);
  gamePlayLayer.draw();
  </code></pre>