diff --git a/core/misc/dialog.ajax.js b/core/misc/dialog.ajax.js
index bae03bf..8bb6599 100644
--- a/core/misc/dialog.ajax.js
+++ b/core/misc/dialog.ajax.js
@@ -9,6 +9,8 @@
 
   Drupal.behaviors.dialog = {
     attach: function (context, settings) {
+      var $context = $(context);
+
       // Provide a known 'drupal-modal' DOM element for Drupal-based modal
       // dialogs. Non-modal dialogs are responsible for creating their own
       // elements, since there can be multiple non-modal dialogs at a time.
@@ -16,12 +18,19 @@
         $('<div id="drupal-modal" />').hide().appendTo('body');
       }
 
-      // If a new form is being attached inside a dialog, remove and replace
-      // the dialog buttons with those from the new form.
-      var $dialog = $(context).closest('.ui-dialog-content');
-      if ($dialog && $dialog.dialog('option', 'drupalAutoButtons')) {
-        var buttons = Drupal.behaviors.dialog.prepareDialogButtons($dialog);
-        $dialog.dialog('option', 'buttons', buttons);
+      // Special behaviors specific when attaching content within a dialog.
+      // These behaviors usually fire after a validation error inside a dialog.
+      var $dialog = $context.closest('.ui-dialog-content');
+      if ($dialog.length) {
+        // Remove and replace the dialog buttons with those from the new form.
+        if ($dialog.dialog('option', 'drupalAutoButtons')) {
+          var buttons = Drupal.behaviors.dialog.prepareDialogButtons($dialog);
+          $dialog.dialog('option', 'buttons', buttons);
+        }
+        // Refocus the first input element after validation errors.
+        if ($context.find('form').length) {
+          $context.find('input:first').focus();
+        }
       }
     },
     detach: function (context, settings) {
@@ -40,19 +49,29 @@
       var buttons = [];
       var $buttons = $dialog.find('.form-actions input[type=submit]');
       $buttons.each(function () {
-        var $originalButton = $(this).hide();
+        // Hidden form buttons need special attention. For browser consistency,
+        // the button needs to be "visible" in order to have the enter key fire
+        // the form submit event. So instead of a simple "hide" or
+        // "display: none", we set its dimensions to zero.
+        // See http://mattsnider.com/how-forms-submit-when-pressing-enter/
+        var $originalButton = $(this).css({
+          width: 0,
+          height: 0,
+          padding: 0,
+          border: 0
+        });
         buttons.push({
           'text': $originalButton.html() || $originalButton.attr('value'),
           'class': $originalButton.attr('class'),
           'click': function (e) {
-            $originalButton.trigger('mousedown');
+            $originalButton.trigger('click');
             e.preventDefault();
           }
         });
       });
       if ($buttons.length) {
         $dialog.find('form').on('submit.dialogSubmit', function (e) {
-          $buttons.first().trigger('mousedown');
+          $buttons.first().trigger('click');
           e.preventDefault();
         });
       }
diff --git a/core/modules/edit/css/edit.module.css b/core/modules/edit/css/edit.module.css
index 6a5ac83..bbe7d05 100644
--- a/core/modules/edit/css/edit.module.css
+++ b/core/modules/edit/css/edit.module.css
@@ -94,7 +94,7 @@
 
 /* Highlighted (hovered) editable. */
 .edit-editable.edit-highlighted {
-  z-index: 305;
+  z-index: 99;
   min-width: 200px;
 }
 .edit-field.edit-editable.edit-highlighted,
@@ -221,7 +221,7 @@
   border: 0;
   margin: 0;
   vertical-align: baseline;
-  z-index: 310;
+  z-index: 100;
 }
 .edit-toolbar-container {
   -webkit-user-select: none;
diff --git a/core/modules/editor/lib/Drupal/editor/Form/EditorImageDialog.php b/core/modules/editor/lib/Drupal/editor/Form/EditorImageDialog.php
index 0a913bd..0fa6249 100644
--- a/core/modules/editor/lib/Drupal/editor/Form/EditorImageDialog.php
+++ b/core/modules/editor/lib/Drupal/editor/Form/EditorImageDialog.php
@@ -101,6 +101,7 @@ public function buildForm(array $form, array &$form_state, FilterFormat $filter_
       '#submit' => array(),
       '#ajax' => array(
         'callback' => array($this, 'submitForm'),
+        'event' => 'click',
       ),
     );
 
diff --git a/core/modules/editor/lib/Drupal/editor/Form/EditorLinkDialog.php b/core/modules/editor/lib/Drupal/editor/Form/EditorLinkDialog.php
index ce2b5c7..4e17831 100644
--- a/core/modules/editor/lib/Drupal/editor/Form/EditorLinkDialog.php
+++ b/core/modules/editor/lib/Drupal/editor/Form/EditorLinkDialog.php
@@ -68,6 +68,7 @@ public function buildForm(array $form, array &$form_state, FilterFormat $filter_
       '#submit' => array(),
       '#ajax' => array(
         'callback' => array($this, 'submitForm'),
+        'event' => 'click',
       ),
     );