ability to switch between singleTile true and false

lib/OpenLayers/Layer/Grid.js

@@ -393,6 +393,30 @@ OpenLayers.Layer.Grid = OpenLayers.Class(OpenLayers.Layer.HTTPRequest, {
             this.gridLayout = null;
         }
     },
+
+   /**
+    * APIMethod: addOptions
+    * 
+    * Parameters:
+    * newOptions - {Object}
+    * reinitialize - {Boolean} If set to true, and if resolution options of the
+    *     current baseLayer were changed, the map will be recentered to make
+    *     sure that it is displayed with a valid resolution, and a
+    *     changebaselayer event will be triggered.
+    */
+    addOptions: function (newOptions, reinitialize) {
+        OpenLayers.Layer.HTTPRequest.prototype.addOptions.apply(this, arguments);
+        if (newOptions.singleTile !== undefined) {
+            this.clearGrid();
+            if (newOptions.singleTile === true) {
+                this.setTileSize();
+                this.initSingleTile(this.map.getExtent());
+            } else {
+                this.tileSize = this.options.tileSize || this.map.getTileSize();
+                this.initGriddedTiles(this.map.getExtent());
+            }
+        }
+    },
     
     /**
      * APIMethod: clone