Use synchronous request for creating new notebooks

To get round popup blockers

IPython/html/static/notebook/js/menubar.js

@@ -91,6 +91,7 b' define(['
             // notebook's path.
             that.contents.new(that.notebook.notebook_path, null, {
                     ext: ".ipynb",
+                    extra_settings: {async: false},  // So we can open a new window afterwards
                     success: function (data) {
                         window.open(
                             utils.url_join_encode(

IPython/html/static/services/contents.js

@@ -118,6 +118,9 b' define(['
             success : options.success || function() {},
             error : this.create_basic_error_handler(options.error)
         };
+        if (options.extra_settings) {
+            $.extend(settings, options.extra_settings);
+        }
         $.ajax(this.api_url(path), settings);
     };
 

IPython/html/static/tree/js/main.js

@@ -62,6 +62,7 b' require(['
     $('#new_notebook').click(function (e) {
         contents.new(common_options.notebook_path, null, {
                 ext: ".ipynb",
+                extra_settings: {async: false},  // So we can open a new window afterwards
                 success: function (data) {
                     window.open(
                         utils.url_join_encode(