diff --git a/elements/urth-core-behaviors/jupyter-notebook-env.html b/elements/urth-core-behaviors/jupyter-notebook-env.html
index 548539ee..eedbd87d 100644
--- a/elements/urth-core-behaviors/jupyter-notebook-env.html
+++ b/elements/urth-core-behaviors/jupyter-notebook-env.html
@@ -9,7 +9,7 @@
 <script>
     'use strict';
     (function() {
-        window.Urth = window.Urth || {};
+        var Urth = window.Urth = window.Urth || {};
 
         /**
          * Behavior that contains notebook related properties
@@ -22,7 +22,7 @@
             properties: {
                 _baseURL: {
                     value: function(){
-                        return window['IPython'] ? IPython.notebook.base_url : '/';
+                        return Urth._baseURL;
                     }
                 },
 
diff --git a/elements/urth-core-behaviors/jupyter-widget-behavior.html b/elements/urth-core-behaviors/jupyter-widget-behavior.html
index cca738c0..a9d5be06 100644
--- a/elements/urth-core-behaviors/jupyter-widget-behavior.html
+++ b/elements/urth-core-behaviors/jupyter-widget-behavior.html
@@ -10,7 +10,7 @@
 <script>
     'use strict';
     (function() {
-        window.Urth = window.Urth || {};
+        var Urth = window.Urth = window.Urth || {};
 
         /**
          * Behavior that encapsulate some of the functions needed by
@@ -45,7 +45,7 @@
 
             _doCreateModel: function(){
                 console.debug('Urth.JupyterWidgetBehavior createModel', this.kernelClass);
-                IPython.notebook.kernel.widget_manager.new_widget(
+                Urth.widget_manager.new_widget(
                     {
                         model_name: 'DeclWidgetModel',
                         widget_class: this.kernelClass
diff --git a/nb-extension/js/init/init.js b/nb-extension/js/init/init.js
index f0d9c320..81a0193c 100644
--- a/nb-extension/js/init/init.js
+++ b/nb-extension/js/init/init.js
@@ -177,14 +177,21 @@ define([
         window.Polymer.dom = 'shadow';
 
         // Expose the base URL being used.
-        window.Urth = window.Urth || {};
+        var Urth = window.Urth = window.Urth || {};
 
         // Global promise which is resolved when widgets are fully initialized
-        window.Urth.widgets = window.Urth.widgets || {};
-        window.Urth.widgets.whenReady = $.Deferred();
+        Urth.widgets = Urth.widgets || {};
+        Urth.widgets.whenReady = $.Deferred();
 
         // expose suppressErrors, false by default to display errors
-        window.Urth.suppressErrors = config.suppressErrors;
+        Urth.suppressErrors = config.suppressErrors;
+
+        if (config.WidgetManager) {
+            Urth.widget_manager = config.WidgetManager;
+        } else if (window.IPython) {
+            // backwards compatibility
+            Urth.widget_manager = window.IPython.notebook.kernel.widget_manager;
+        }
 
         isServerExtensionAvailable(baseURL + COMPONENTS_DIR, function(isAvailable){
             console.log('Server extension is ' + (isAvailable ? '' : 'NOT ') + 'available!');
@@ -195,7 +202,8 @@ define([
                 ? baseURL
                 : getModuleBasedComponentRoot(module);
 
-            window.Urth.BASE_URL = components_root;
+            Urth.BASE_URL = components_root;
+            Urth._baseURL = baseURL;
             components_root += COMPONENTS_DIR;
 
             loadPolyfill(components_root, function() {
@@ -206,6 +214,6 @@ define([
             });
         });
 
-        return window.Urth.widgets.whenReady;
+        return Urth.widgets.whenReady;
     };
 });