Extending Map.js documentation to include comment regarding destroy from

#2277.


git-svn-id: http://svn.openlayers.org/trunk/openlayers@11454 dc9f47b5-9b13-0410-9fdd-eb0c1a62fdaf

lib/OpenLayers/Map.js

@@ -643,7 +643,15 @@ OpenLayers.Map = OpenLayers.Class({
 
     /**
      * APIMethod: destroy
-     * Destroy this map
+     * Destroy this map.
+     *    Note that if you are using an application which removes a container
+     *    of the map from the DOM, you need to ensure that you destroy the
+     *    map *before* this happens; otherwise, the page unload handler
+     *    will fail because the DOM elements that map.destroy() wants
+     *    to clean up will be gone. (See 
+     *    http://trac.osgeo.org/openlayers/ticket/2277 for more information).
+     *    This will apply to GeoExt and also to other applications which
+     *    modify the DOM of the container of the OpenLayers Map.
      */
     destroy:function() {
         // if unloadDestroy is null, we've already been destroyed