title: In Google Maps V3, how can I get a draggable marker to pan the map?
body: <p>I have found several V2 examples of how to pan the map while a marker is being dragged.  For example:  <a href="http://www.putyourlightson.net/projects/coordinates" rel="noreferrer">http://www.putyourlightson.net/projects/coordinates</a></p>
  
  <pre><code>    // create map and add controls
  var map = new GMap2(document.getElementById("map"));
  map.addControl(new GLargeMapControl());        
  map.addControl(new GMapTypeControl());
  
  // set centre point of map
  var centrePoint = new GLatLng('53.34870686020199', '-6.267356872558594');
  map.setCenter(centrePoint, 14); 
  
  // add a draggable marker
  var marker = new GMarker(centrePoint, {draggable: true});
  map.addOverlay(marker);
  
  // add a drag listener to the map
  GEvent.addListener(marker, "dragend", function() {
      var point = marker.getPoint();
      map.panTo(point);
      document.getElementById("latitude").value = point.lat();
      document.getElementById("longitude").value = point.lng();
  });
  </code></pre>
  
  <p>This page seems to "auto-pan" while the marker is being dragged; note that its only event listener is for "dragend".  But I assure you that that map pans while the marker is being dragged.</p>
  
  <p>I am trying to achieve the same thing with the V3 API, without any success.  I even tried calling map.panTo() while the icon is being dragged, with unsatisfying results:  <a href="http://www.publicgloucester.com/test.html" rel="noreferrer">http://www.publicgloucester.com/test.html</a></p>
  
  <pre><code>function initialize ()
     {
     Gloucester = new google.maps.LatLng (42.6159285, -70.6619888);
  
     myOptions = 
        {
        zoom: 14,
        mapTypeId: google.maps.MapTypeId.ROADMAP,
        center: Gloucester,
        streetViewControl: false
        }
  
     map = new google.maps.Map (document.getElementById ("map_canvas"), myOptions);
  
     marker = new google.maps.Marker ({position: Gloucester, title: "Gloucester, MA"});
     marker.setMap (map);
     marker.setDraggable (true);
  
     google.maps.event.addListener (marker, 'drag', function (event) 
        {
        // Pan to this position (doesn't work!)
        map.panTo (marker.getPosition());
        });
  
     }
  </code></pre>
  
  <p>It makes sense to me that this wouldn't work, since panning to place the marker in the center of the map, while the map is moving, is bogus.</p>
  
  <p>Is it as simple as the V2 API doing this automatically, while the V3 API does not?  How can I achieve this effect with the V3 API?</p>
  
  <p>Thanks.</p>