diff --git a/core/modules/outside_in/js/offcanvas.js b/core/modules/outside_in/js/offcanvas.js
index 88531dd..de6f0c7 100644
--- a/core/modules/outside_in/js/offcanvas.js
+++ b/core/modules/outside_in/js/offcanvas.js
@@ -79,14 +79,12 @@
    *   Object holding the server response.
    * @param {number} [status]
    *   The HTTP status code.
-   *
-   * @return {bool}
-   *   Returns false.
    */
   Drupal.AjaxCommands.prototype.openOffCanvas = function (ajax, response, status) {
-    // Set animation duration and get #page-wrapper width.
+    // Discover display/viewport size.  TODO:  work in breakpoints for tray size.
     var $pageWrapper = $('#canvas-tray-wrapper');
     var pageWidth = $pageWrapper.width();
+
     // Set the initial state of the off canvas element.
     // If the state has been set previously, use it.
     Drupal.offCanvas = {
@@ -104,19 +102,19 @@
     // Put everything together.
     $offcanvasWrapper.append([$offcanvasClose, $title, $offcanvasContent]);
 
-    // Only add off canvas elements if we have none visible.
+    // Handle opening or updating tray with content.
     if (!Drupal.offCanvas.visible) {
-      // Append off canvas wrapper to the 'page'
+      // Append content then open tray.
       $pageWrapper.append($offcanvasWrapper);
       Drupal.offCanvas.visible = true;
       $pageWrapper.addClass('js-tray-open');
+      Drupal.announce(Drupal.t('Configuration tray opened.'));
     } else {
-      // If tray already open, remove content add new.
+      // Remove previous content then append new content.
       $pageWrapper.find('#offcanvas').remove();
       $pageWrapper.append($offcanvasWrapper);
+      Drupal.announce(Drupal.t('Configuration tray content has been updated.'));
     }
-
-    return false;
   };
 
 })(jQuery, Drupal);