Show notification on course outline reorder.

cms/djangoapps/contentstore/features/course-overview.feature

@@ -63,3 +63,10 @@ Feature: Course Overview
         When I navigate to the course overview page
         And I change an assignment's grading status
         Then I am shown a notification
+
+   Scenario: Notification is shown on subsection reorder
+        Given I have opened a new course section in Studio
+        And I have added a new subsection
+        And I have added a new subsection
+        When I reorder subsections
+        Then I am shown a notification

cms/djangoapps/contentstore/features/course-overview.py

@@ -124,3 +124,14 @@ def all_sections_are_collapsed(step):
 def change_grading_status(step):
     world.css_find('a.menu-toggle').click()
     world.css_find('.menu li').first.click()
+
+
+@step(u'I reorder subsections')
+def reorder_subsections(_step):
+    draggable_css = 'a.drag-handle'
+    ele = world.css_find(draggable_css).first
+    ele.action_chains.drag_and_drop_by_offset(
+        ele._element,
+        30,
+        0
+    ).perform()

cms/static/js/views/overview.js

@@ -225,12 +225,19 @@ function _handleReorder(event, ui, parentIdField, childrenSelector) {
                 ui.draggable.attr("style", "position:relative;"); // STYLE hack too
                 children.push(ui.draggable.data('id'));
         }
+        var saving = new CMS.Views.Notification.Mini({
+            title: gettext('Saving') + '…'
+        });
+        saving.show();
         $.ajax({
                 url: "/save_item",
                 type: "POST",
                 dataType: "json",
                 contentType: "application/json",
-                data:JSON.stringify({ 'id' : subsection_id, 'children' : children})
+                data:JSON.stringify({ 'id' : subsection_id, 'children' : children}),
+                success: function() {
+                    saving.hide();
+                }
         });
 
 }