title: Google Maps v3 setting a circle with editable radius but not center
body: <p>I have managed to put a circle on a map and make it editable:</p>
  
  <pre><code>var circle = new google.maps.Circle({
            map: map,
            radius: 1609.344, // 1 mile
            editable: true,
            fillOpacity: 0.25
          });
  
  
  circle.bindTo('center', marker, 'position');
  </code></pre>
  
  <p>However, this makes both the radius, and center editable. I only want the radius to be editable. I can't see a way to have that level of control via <code>google.maps.Circle</code>.</p>
  
  <p>What I am after, is pretty much what is here:</p>
  
  <p><a href="http://www.freemaptools.com/radius-around-point.htm" rel="noreferrer">http://www.freemaptools.com/radius-around-point.htm</a></p>
  
  <p>However I can't see how it is done as their code looks obfuscated.</p>