Notes about Google.v3 layers (see #484)

notes/2.13.md

@@ -16,6 +16,16 @@ Corresponding issues/pull requests:
 
  * https://github.com/openlayers/openlayers/pull/483
 
+## Google v3 Layer
+
+This release changes the way Google layers are integrated with OpenLayers. With this change, OpenLayers should be less fragile to changes of the GMaps API version, because no DOM elements inside the Google container need to be modified by OpenLayers any more.
+
+Application developers should be aware that the Google Map of an `OpenLayers.Layer.Google.v3` instance is no longer added to the map's `viewPortDiv`. Instead, the `viewPortDiv` is added as Google Maps control to the Google map. This means that when switching base layers, the whole DOM structure below the map's `div` changes.
+
+Corresponding issues/pull requests:
+
+* https://github.com/openlayers/openlayers/pull/484
+
 # Behavior Changes from Past Releases
 
 ## window.$ is no longer an alias for OpenLayers.Util.getElement