make the KeyboardDefaults control prevent browser default after handling a key press

lib/OpenLayers/Control/KeyboardDefaults.js

@@ -62,7 +62,7 @@ OpenLayers.Control.KeyboardDefaults = OpenLayers.Class(OpenLayers.Control, {
      * evt - {Event} 
      */
     defaultKeyPress: function (evt) {
-        var size;
+        var size, handled = true;
         switch(evt.keyCode) {
             case OpenLayers.Event.KEY_LEFT:
                 this.map.pan(-this.slideFactor, 0);
@@ -106,7 +106,14 @@ OpenLayers.Control.KeyboardDefaults = OpenLayers.Class(OpenLayers.Control, {
             case 95:  // -/_ (some ASCII)
                 this.map.zoomOut();
                 break; 
-        } 
+            default:
+                handled = false;
+        }
+        if (handled) {
+            // prevent browser default not to move the page
+            // when moving the page with the keyboard
+            OpenLayers.Event.stop(evt);
+        }
     },
 
     CLASS_NAME: "OpenLayers.Control.KeyboardDefaults"