diff --git a/core/modules/contextual/contextual.module b/core/modules/contextual/contextual.module
index 76e39ba..5fd3786 100644
--- a/core/modules/contextual/contextual.module
+++ b/core/modules/contextual/contextual.module
@@ -14,7 +14,6 @@ function contextual_toolbar() {
   }
 
   $tab['contextual'] = array(
-    '#type' => 'toolbar_item',
     'tab' => array(
       '#type' => 'html_tag',
       '#tag' => 'button',
@@ -27,6 +26,7 @@ function contextual_toolbar() {
       // @todo remove this once http://drupal.org/node/1908906 lands.
       '#options' => array('attributes' => array()),
     ),
+    '#theme_wrappers' => array('toolbar_tab_wrapper'),
     '#wrapper_attributes' => array(
       'class' => array('element-hidden', 'contextual-toolbar-tab'),
     ),
diff --git a/core/modules/contextual/contextual.toolbar.js b/core/modules/contextual/contextual.toolbar.js
index f1e6f9f..45f9757 100644
--- a/core/modules/contextual/contextual.toolbar.js
+++ b/core/modules/contextual/contextual.toolbar.js
@@ -34,8 +34,7 @@ Drupal.behaviors.contextualToolbar = {
         })
         .on('drupalOverlayClose.contextualToolbar', function () {
           model.set('isVisible', true);
-        })
-        .on('drupalEditModeChanged', Drupal.contextualToolbar.editModeChangedHandler);
+        });
 
       // Update the model to show the edit tab if there's >=1 contextual link.
       if ($contextuals.length > 0) {
@@ -57,13 +56,7 @@ Drupal.behaviors.contextualToolbar = {
   }
 };
 
-Drupal.contextualToolbar = Drupal.contextualToolbar || {
-  models: {},
-  views: {},
-  editModeChangedHandler: function (event, data) {
-    Drupal.toolbar.setActiveItem($('.js .toolbar .bar .contextual-toolbar-tab'));
-  }
-};
+Drupal.contextualToolbar = Drupal.contextualToolbar || { models: {}, views: {}};
 
 /**
  * Backbone Model for the edit toggle.
diff --git a/core/modules/shortcut/shortcut.module b/core/modules/shortcut/shortcut.module
index 3a75378..c4990b7 100644
--- a/core/modules/shortcut/shortcut.module
+++ b/core/modules/shortcut/shortcut.module
@@ -580,7 +580,7 @@ function shortcut_toolbar() {
         '#options' => array(
           'attributes' => array(
             'title' => t('Shortcuts'),
-            'class' => array('icon', 'icon-shortcut', 'toolbar-tab'),
+            'class' => array('icon', 'icon-shortcut', 'toolbar-tab',),
           ),
         ),
       ),
diff --git a/core/modules/toolbar/js/toolbar.js b/core/modules/toolbar/js/toolbar.js
index 344c69e..7b21a2b 100644
--- a/core/modules/toolbar/js/toolbar.js
+++ b/core/modules/toolbar/js/toolbar.js
@@ -27,41 +27,42 @@ Drupal.behaviors.toolbar = {
       var model = new StateModel({
         locked: JSON.parse(localStorage.getItem('Drupal.toolbar.trayVerticalLocked')) || false,
         activeTab: document.getElementById(JSON.parse(localStorage.getItem('Drupal.toolbar.activeTabID'))),
-        orientation: JSON.parse(localStorage.getItem('Drupal.toolbar.trayOrientation')) || 'vertical',
         mqMatches: mql.matches
       });
 
-      // Respond to external events.
-      $(window)
-        .on('resize.toolbar', Drupal.debounce(function (event) {
-          model.set('dimensionsAreValid', false);
-        }, 150));
-
       // Update the model when matchMedia fires.
       mql.addListener(function (mql) {
         model.set('mqMatches', mql.matches);
       });
 
+      // Respond to viewport offset dimension changes.
+      $(document)
+        .on('drupalViewportOffsetChange.toolbar', function (event, offsets) {
+          model.set('offsets', {
+            top: offsets.top,
+            right: offsets.right,
+            bottom: offsets.bottom,
+            left: offsets.left
+          });
+          // Alter the padding on the top of the body element.
+          $('body').css('padding-top', offsets.top);
+        });
+
       // Respond to toolbar events.
       $(document)
-        .on('drupalViewportOffsetChange.toolbar', Drupal.toolbar.adjustPlacement);
-        .on('drupalToolbarDimensionsChanged.toolbar', dimensionsChangeHandler)
-        .on('drupalToolbarOrientationChanged.toolbar', orientationChangeHandler)
-        .on('drupalToolbarTrayChanged.toolbar', trayChangeHandler);
+        .on('drupalToolbarOrientationChange.toolbar', Drupal.toolbar.orientationChangeHandler)
+        .on('drupalToolbarTrayChange.toolbar', Drupal.toolbar.trayChangeHandler);
 
       // Broadcast model changes to other modules.
       model
-        .on('change:height', function (model, height) {
-          $(document).trigger('drupalToolbarDimensionsChanged', height);
-        })
         .on('change:orientation', function (model, orientation) {
           $(document).trigger('drupalToolbarOrientationChange', orientation);
         })
         .on('change:activeTab', function (model, tab) {
-          $(document).trigger('drupalToolbarTabChanged', tab);
+          $(document).trigger('drupalToolbarTabChange', tab);
         })
         .on('change:activeTray', function (model, tray) {
-          $(document).trigger('drupalToolbarTrayChanged', tray);
+          $(document).trigger('drupalToolbarTrayChange', tray);
         });
 
       // Build the toolbar view and assign it to the closure variable reference.
@@ -101,40 +102,48 @@ Drupal.behaviors.toolbar = {
 };
 
 // Expose a limited public API.
-  Drupal.toolbar = Drupal.toolbar || {
-    /**
-     * Accepts a list of subtree menu elements.
-     *
-     * A deferred object that is resolved by an inlined JavaScript callback.
-     *
-     * JSONP callback.
-     * @see toolbar_subtrees_jsonp().
-     */
-    setSubtrees: new $.Deferred(),
-
-    /**
-     *
-     */
-    setActiveItem: function (element) {
-      var item;
-      if (typeof element === 'object') {
-        // Check if the element is a DOM element.
-        if ('tagName' in element) {
-          item = element;
-        }
-        // Check if the element is a jQuery set.
-        if ('jquery' in element) {
-          item = element.get(0);
-        }
-      }
-      else if (!element) {
-        item = element;
-      }
-      if (this.model && item) {
-        this.model.set('activeTab', item);
-      }
-    }
-  };
+Drupal.toolbar = Drupal.toolbar || {
+  /**
+   * Accepts a list of subtree menu elements.
+   *
+   * A deferred object that is resolved by an inlined JavaScript callback.
+   *
+   * JSONP callback.
+   * @see toolbar_subtrees_jsonp().
+   */
+  setSubtrees: new $.Deferred(),
+
+  /**
+   * Responds to drupalToolbarOrientationChange.
+   *
+   * Applies classes to the body element that reflect the current orientation
+   * of the active toolbar.
+   *
+   * @param jQuery.Event event
+   * @param string orientation
+   *   The value can be either 'horizontal' or 'vertical'.
+   */
+  orientationChangeHandler: function (event, orientation) {
+    $('body')
+      .toggleClass('toolbar-vertical', orientation === 'vertical')
+      .toggleClass('toolbar-horizontal', orientation === 'horizontal');
+  },
+
+  /**
+   * Responds to drupalToolbarTrayChange.
+   *
+   * Toggles the toolbar-tray-open class on the body elment. The class is applied
+   * when a toolbar tray is active.
+   *
+   * @param jQuery.Event event
+   * @param DOM tray
+   *   The currently active tray DOM element.
+   */
+  trayChangeHandler: function (event, tray) {
+    $('body')
+      .toggleClass('toolbar-tray-open', !!tray);
+  }
+};
 
 /**
  * Backbone model for the toolbar.
@@ -159,9 +168,15 @@ var StateModel = Backbone.Model.extend({
     mqMatches: null,
     // The height of the toolbar.
     height: null,
-    // Whether the current dimensions are valid. Dimensions can be invalidated
-    // by a screen resize.
-    dimensionsAreValid: true
+    // The current viewport offsets determined by Drupal.displace(). The offsets
+    // suggest how a module might position is components relative to the
+    // viewport.
+    offsets: {
+      top: 0,
+      right: 0,
+      bottom: 0,
+      left: 0
+    }
   }
 });
 
@@ -183,7 +198,7 @@ var ToolbarView = Backbone.View.extend({
     this.model.on('change:activeTab', this.render, this);
     this.model.on('change:orientation', this.render, this);
     this.model.on('change:mqMatches', this.onMediaQueryChange, this);
-    this.model.on('change:dimensionsAreValid', this.setHeight, this);
+    this.model.on('change:offsets', this.adjustPlacement, this);
 
     // Add the tray orientation toggles.
     this.$el.find('.tray')
@@ -191,25 +206,29 @@ var ToolbarView = Backbone.View.extend({
       .append(Drupal.theme('toolbarOrientationToggle'));
 
     // Update the tray orientation.
-    if (!this.model.get('locked')) {
-      var orientation = this._getTrayOrientation(this.model.get('mqMatches'));
-      // This model change is silent because this is the initialization phase.
-      this.model.set('orientation', orientation, { silent: true });
-    }
+    var orientation = this._checkOrientationLock(this._getTrayOrientation(this.model.get('mqMatches')));
+    // This model change is silent because it will be triggered below when
+    // change:activeTab is triggered.
+    this.model.set('orientation', orientation, {silent: true});
 
     // Trigger an activeTab change so that listening scripts can respond on
     // page load. This will call render.
     this.model.trigger('change:activeTab');
+
+    // Invoke Drupal.displace() to get the current viewport offset values.
+    Drupal.displace();
   },
 
   /**
    * Implements Backbone.View.prototype.render().
+   *
+   * @return Backbone.View
    */
-  render: function (model, property) {
+  render: function () {
     // Update the display of the tabs.
     this.refreshTabs();
     // Adjust the orientation of the active tray.
-    this.changeOrientation();
+    this.setOrientation();
     // Adjust the height of the toolbar.
     this.model.set('dimensionsAreValid', false);
 
@@ -217,7 +236,9 @@ var ToolbarView = Backbone.View.extend({
   },
 
   /**
-   * Toolbar tab click event handler; sets activeTab.
+   * Responds to a toolbar tab click.
+   *
+   * @param jQuery.Event event
    */
   onTabClick: function (event) {
     var tab = this.model.get('activeTab');
@@ -230,7 +251,9 @@ var ToolbarView = Backbone.View.extend({
   },
 
   /**
-   * Orientation toggle click event handler; toggles orientation.
+   * Toggles the orientation of a toolbar tray.
+   *
+   * @param jQuery.Event event
    */
   onOrientationToggleClick: function (event) {
     var orientation = this.model.get('orientation');
@@ -255,19 +278,22 @@ var ToolbarView = Backbone.View.extend({
   },
 
   /**
-   * Model change handler; updates tray orientation.
+   * Responds to change:orientation event when window.matchMedia fires.
+   *
+   * @param Backbone.Model model
+   * @param boolean mqMatches
+   *   The matches property of a MediaQueryList object.
    */
   onMediaQueryChange: function (model, mqMatches) {
-    this.model.set('orientation', this._getTrayOrientation(mqMatches));
+    this.model.set('orientation', this._checkOrientationLock(this._getTrayOrientation(mqMatches)));
   },
 
   /**
    * Gets the tray orientation depending on whether the media query matches.
    *
-   * @param Boolean mqMatches
-   *   Indicates whether the media query matches.
-   *
-   * @return String
+   * @param boolean mqMatches
+   *   The matches property of a MediaQueryList object.
+   * @return string
    *   The orientation, either 'horizontal' or 'vertical'.
    */
   _getTrayOrientation: function (mqMatches) {
@@ -276,6 +302,8 @@ var ToolbarView = Backbone.View.extend({
 
   /**
    * Toggles a toolbar tab and the associated tray.
+   *
+   * @param jQuery.Event event
    */
   refreshTabs: function (event) {
     var $tab = $(this.model.get('activeTab'));
@@ -327,15 +355,11 @@ var ToolbarView = Backbone.View.extend({
   /**
    * Change the orientation of the tray between vertical and horizontal.
    */
-  changeOrientation: function () {
-    var orientation = this.model.get('orientation');
+  setOrientation: function () {
+    var orientation = this._checkOrientationLock(this.model.get('orientation'));
+    // The antiOrientation is used to render the view of action buttons like
+    // the tray orientation toggle.
     var antiOrientation = (orientation === 'vertical') ? 'horizontal' : 'vertical';
-    var locked = this.model.get('locked');
-    // Set the orientation of the tray.
-    // If the tray is locked to vertical in localStorage, persist the vertical
-    // presentation. If the tray is not locked to vertical, let the media
-    // query application decide the orientation.
-    orientation = (locked) ? 'vertical' : orientation;
     // Update the orientation of the trays.
     var $trays = this.$el.find('.tray')
       .removeClass('horizontal vertical')
@@ -350,6 +374,17 @@ var ToolbarView = Backbone.View.extend({
       .removeClass(iconClass)
       .addClass(iconAntiClass);
 
+    var dir = document.documentElement.dir;
+    var edge = (dir === 'rtl') ? 'right' : 'left';
+    // Remove data-offset attributes from the trays so they can be refreshed.
+    $trays.removeAttr('data-offset-left data-offset-right data-offset-top');
+    // If an active vertical tray exists, mark it as an offset element.
+    $trays.filter('.vertical.active').attr('data-offset-' + edge, '');
+    // If an active horizontal tray exists, mark it as an offset element.
+    $trays.filter('.horizontal.active').attr('data-offset-top', '');
+    // Trigger a recalculation of viewport displacing elements.
+    Drupal.displace();
+
     // Append a message that the tray orientation has been changed.
     Drupal.announce(Drupal.t('Tray orientation changed to @orientation.', {
       '@orientation': orientation
@@ -357,17 +392,29 @@ var ToolbarView = Backbone.View.extend({
   },
 
   /**
-   * The height of the toolbar offsets the top of the page content.
+   * Returns an orientation based on the orientation lock.
    *
-   * Page components can register with the offsettopchange event to know when
-   * the height of the toolbar changes.
+   * Orientation is locked to the vertical position when a user changes a
+   * horizontal tray to a vertical try using the tray orientation toggle button.
+   *
+   * @param string orientation
+   *   The value can be either 'horizontal' or 'vertical'.
+   * @return string
+   *   The orientation, either 'horizontal' or 'vertical'.
    */
-  setHeight: function (model, dimensionsAreValid) {
-    // Don't reprocess unless the current dimensions have been invalidated.
-    if (dimensionsAreValid) {
-      return;
-    }
-    var originalHeight = this.model.get('height');
+  _checkOrientationLock: function (orientation) {
+    var locked = this.model.get('locked');
+    // Set the orientation of the tray.
+    // If the tray is locked to vertical in localStorage, persist the vertical
+    // presentation. If the tray is not locked to vertical, let the media
+    // query application decide the orientation.
+    return (locked) ? 'vertical' : orientation;
+  },
+
+  /**
+   * Sets the tops of the trays so that they align with the bottom of the bar.
+   */
+  adjustPlacement: function () {
     // Set the top of the all the trays to the height of the bar.
     var barHeight = this.$el.find('.bar').outerHeight();
     var height = barHeight;
@@ -380,67 +427,10 @@ var ToolbarView = Backbone.View.extend({
         tray.style.top = bhpx;
       }
     }
-    /**
-     * Get the height of the active tray and include it in the total
-     * height of the toolbar.
-     */
-    height += $trays.filter('.active.horizontal').outerHeight() || 0;
-    // Indicate the height of the toolbar in the attribute data-offset-top.
-    var offset = parseInt(this.$el.attr('data-offset-top'), 10);
-    if (originalHeight !== height) {
-      this.$el.attr('data-offset-top', height);
-      this.model.set('height', height);
-    }
-    this.model.set('dimensionsAreValid', true);
   }
 });
 
 /**
- * Repositions trays and sets body padding according to the height of the bar.
- *
- * @param {Event} event
- *   - jQuery Event object.
- *
- * @param {Object} offsets
- *   - Contains for keys -- top, right, bottom and left -- that indicate the
- *   viewport offset distances calculated by Drupal.displace().
- */
-Drupal.toolbar.adjustPlacement = function (event, offsets) {
-  // Set the top of the all the trays to the height of the bar.
-  var barHeight = $toolbar.find('.bar').outerHeight();
-  var height = barHeight;
-  var bhpx =  barHeight + 'px';
-  var tray;
-  for (var i = 0, il = $trays.length; i < il; i++) {
-    tray = $trays[i];
-    if (!tray.style.top.length || (tray.style.top !== bhpx)) {
-      tray.style.top = bhpx;
-    }
-  }
-  // Alter the padding on the top of the body element.
-  $('body').css('padding-top', offsets.top);
-};
-
-/**
- * Sets the width of a vertical tray in a data attribute.
- *
- * If the width of the tray changed, Drupal.displace is called so that elements
- * can adjust to the placement of the tray.
- */
-Drupal.toolbar.setTrayWidth = function () {
-  var dir = document.documentElement.dir;
-  var edge = (dir === 'rtl') ? 'right' : 'left';
-  // Remove the left offset from the trays.
-  $toolbar.find('.tray').removeAttr('data-offset-' + edge + ' data-offset-top');
-  // If an active vertical tray exists, mark it as an offset element.
-  $toolbar.find('.tray.vertical.active').attr('data-offset-' + edge, '');
-  // If an active horizontal tray exists, mark it as an offset element.
-  $toolbar.find('.tray.horizontal.active').attr('data-offset-top', '');
-  // Trigger a recalculation of viewport displacing elements.
-  Drupal.displace();
-};
-
-/**
  * Backbone Model for collapsible menus.
  */
 var MenuStateModel = Backbone.Model.extend({
@@ -464,7 +454,7 @@ var MenuView = Backbone.View.extend({
   /**
    * Implements Backbone.View.prototype.render().
    */
-  render: function (model, property) {
+  render: function () {
     var subtrees = this.model.get('subtrees');
     // Add subtrees.
     // @todo Optimize this to delay adding each subtree to the DOM until it is
@@ -485,39 +475,8 @@ var MenuView = Backbone.View.extend({
         .drupalToolbarMenu();
     }
   }
-
 });
 
-
-
-/**
- *
- */
-function dimensionsChangeHandler (event, height) {
-  // Alter the padding on the top of the body element.
-  $('body')
-    .css('padding-top', height);
-  $(document)
-    .trigger('offsettopchange', height);
-}
-
-/**
- *
- */
-function orientationChangeHandler (event, orientation) {
-  $('body')
-    .toggleClass('toolbar-vertical', orientation === 'vertical')
-    .toggleClass('toolbar-horizontal', orientation === 'horizontal');
-}
-
-/**
- *
- */
-function trayChangeHandler (event, tray) {
-  $('body')
-    .toggleClass('toolbar-tray-open', !!tray);
-}
-
 /**
  * Theme function for the toolbar orientation toggle.
  *
@@ -530,4 +489,4 @@ Drupal.theme.toolbarOrientationToggle = function () {
     '</div></div>';
 };
 
-}(jQuery, Backbone, Drupal, drupalSettings, document, window));
+}(jQuery, Backbone, Drupal, drupalSettings));
diff --git a/core/modules/toolbar/toolbar.module b/core/modules/toolbar/toolbar.module
index 6afa5c2..6645147 100644
--- a/core/modules/toolbar/toolbar.module
+++ b/core/modules/toolbar/toolbar.module
@@ -91,8 +91,6 @@ function toolbar_element_info() {
       // The id cannot be simply "toolbar" or it will clash with the simpletest
       // tests listing which produces a checkbox with attribute id="toolbar"
       'id' => 'toolbar-administration',
-      // The 'overlay-displace-top' class pushes the overlay down, so it appears
-      // below the toolbar.
       'class' => array('toolbar',),
       'role' => 'navigation',
     ),
@@ -284,21 +282,25 @@ function theme_toolbar(&$variables) {
  */
 function toolbar_pre_render_item($element) {
 
+  // Assign each item an unique ID.
+  $id = drupal_html_id('toolbar-item');
+
+  // Provide attributes for a toolbar item.
+  $attributes = array(
+    'id' => $id,
+  );
+
   // If tray content is present, markup the tray and its associated trigger.
   if (!empty($element['tray'])) {
 
-    // Trays are associated with their trigger by a unique ID.
-    $id = drupal_html_id('toolbar-tray');
-    $element['tab']['#tray_id'] = $id;
-
-    // Provide attributes for a tray trigger.
-    $attributes = array(
-      'id' => 'toolbar-tab-' . $id,
-      'data-toolbar-tray' => $id,
+    // Provide attributes necessary for trays.
+    $attributes += array(
+      'data-toolbar-tray' => $id . '-tray',
       'aria-owns' => $id,
       'role' => 'button',
       'aria-pressed' => 'false',
     );
+
     // Merge in module-provided attributes.
     $element['tab'] += array('#attributes' => array());
     $element['tab']['#attributes'] += $attributes;
@@ -306,9 +308,9 @@ function toolbar_pre_render_item($element) {
 
     // Provide attributes for the tray theme wrapper.
     $attributes = array(
-      'id' => $id,
-      'data-toolbar-tray' => $id,
-      'aria-owned-by' => 'toolbar-tab-' . $id,
+      'id' => $id . '-tray',
+      'data-toolbar-tray' => $id . '-tray',
+      'aria-owned-by' => $id,
     );
     // Merge in module-provided attributes.
     if (!isset($element['tray']['#wrapper_attributes'])) {
@@ -485,7 +487,7 @@ function toolbar_toolbar() {
       '#options' => array(
         'attributes' => array(
           'title' => t('Admin menu'),
-          'class' => array('icon', 'icon-menu', 'toolbar-tab'),
+          'class' => array('icon', 'icon-menu', 'toolbar-tab',),
         ),
       ),
     ),
diff --git a/core/modules/tour/js/tour.js b/core/modules/tour/js/tour.js
index b6e8a58..d8885be 100644
--- a/core/modules/tour/js/tour.js
+++ b/core/modules/tour/js/tour.js
@@ -130,7 +130,6 @@ Drupal.tour.views.ToggleTourView = Backbone.View.extend({
    */
   onClick: function (event) {
     this.model.set('isActive', !this.model.get('isActive'));
-    Drupal.toolbar.setActiveItem(event.target);
     event.preventDefault();
     event.stopPropagation();
   },
@@ -202,4 +201,4 @@ Drupal.tour.views.ToggleTourView = Backbone.View.extend({
 
 });
 
-})(jQuery, Backbone, Drupal, document);
+})(jQuery, Backbone, Drupal, document);
\ No newline at end of file
diff --git a/core/modules/user/user.module b/core/modules/user/user.module
index f092329..efd6f65 100644
--- a/core/modules/user/user.module
+++ b/core/modules/user/user.module
@@ -2716,7 +2716,7 @@ function user_toolbar() {
       '#options' => array(
         'attributes' => array(
           'title' => t('My account'),
-          'class' => array('icon', 'icon-user', 'toolbar-tab'),
+          'class' => array('icon', 'icon-user', 'toolbar-tab',),
         ),
       ),
     ),