diff --git a/core/misc/dialog.ajax.js b/core/misc/dialog.ajax.js
index d76baf8..a30e0d9 100644
--- a/core/misc/dialog.ajax.js
+++ b/core/misc/dialog.ajax.js
@@ -4,8 +4,20 @@
  */
 
 (function ($, Drupal) {
+
   "use strict";
 
+  Drupal.behaviors.dialog = {
+    attach: function () {
+      // Provide a known 'drupal-modal' dom element for Drupal code to use for
+      // modal dialogs. Since there can be multiple non-modal dialogs at a time,
+      // it is the responsibility of calling code to create the elements it needs.
+      if (!$('#drupal-modal').length) {
+        $('<div id="drupal-modal" />').hide().appendTo('body');
+      }
+    }
+  };
+
   /**
    * Command to open a dialog.
    */
@@ -23,15 +35,20 @@
       ajax.wrapper = $dialog.attr('id');
     }
 
-    // Open the dialog itself.
-    response.dialogOptions = response.dialogOptions || {};
-    var dialog = new Drupal.dialog($dialog, response.dialogOptions);
-    dialog.open();
-
     // Use the ajax.js insert command to populate the dialog contents.
     response.command = 'insert';
     response.method = 'html';
     ajax.commands.insert(ajax, response, status);
+
+    // Open the dialog itself.
+    response.dialogOptions = response.dialogOptions || {};
+    var dialog = Drupal.dialog($dialog, response.dialogOptions);
+    if (response.dialogOptions.modal) {
+      dialog.showModal();
+    }
+    else {
+      dialog.show();
+    }
   };
 
   /**
@@ -42,22 +59,38 @@
   Drupal.ajax.prototype.commands.closeDialog = function (ajax, response, status) {
     var $dialog = $(response.selector);
     if ($dialog.length) {
-      var dialog = new Drupal.dialog($dialog);
-      dialog.close();
+      Drupal.dialog($dialog).close();
     }
   };
 
   /**
    * Command to set a dialog property.
    *
-   * If no selector is given, it defaults to setting the modal properties.
+   * jQuery UI specific way of setting dialog options.
    */
   Drupal.ajax.prototype.commands.setDialogOption = function (ajax, response, status) {
     var $dialog = $(response.selector);
     if ($dialog.length) {
-      var dialog = new Drupal.dialog($dialog);
-      dialog.element.dialog('option', response.optionName, response.optionValue);
+      $dialog.dialog('option', response.optionName, response.optionValue);
     }
   };
 
+  /**
+   * Binds a listener on dialog creation to handle the cancel link.
+   */
+  $(window).on('dialog:aftercreate', function (e, dialog, $element, settings) {
+    $element.on('click.dialog', '.dialog-cancel', function (e) {
+      dialog.close('cancel');
+      e.preventDefault();
+      e.stopPropagation();
+    });
+  });
+
+  /**
+   * Removes all 'dialog' listeners.
+   */
+  $(window).on('dialog:beforeclose', function (e, dialog, $element) {
+    $element.off('.dialog');
+  });
+
 })(jQuery, Drupal);
diff --git a/core/misc/dialog.js b/core/misc/dialog.js
index 1ddc93c..9f6f29c 100644
--- a/core/misc/dialog.js
+++ b/core/misc/dialog.js
@@ -10,64 +10,46 @@
 
 drupalSettings.dialog = {
   autoOpen: true,
-  dialogClass: ''
-};
-
-Drupal.behaviors.dialog = {
-  attach: function () {
-    // Provide a known 'drupal-modal' dom element for Drupal code to use for
-    // modal dialogs. Since there can be multiple non-modal dialogs at a time,
-    // it is the responsibility of calling code to create the elements it needs.
-    if (!$('#drupal-modal').length) {
-      $('<div id="drupal-modal" />').hide().appendTo('body');
-    }
+  dialogClass: '',
+  close: function (e) {
+    Drupal.detachBehaviors(e.target, null, 'unload');
   }
 };
 
 Drupal.dialog = function (element, options) {
-  // Set a default for options, making it optional.
-  options = options ? options : {};
-
-  this.element = $(element);
-  this.isOpen = false;
-  this.returnValue = undefined;
-  this.options = $.extend({}, drupalSettings.dialog, options);
-};
 
-Drupal.dialog.prototype.open = function (options) {
-  options = $.extend({}, drupalSettings.dialog, this.options, options);
+  function openDialog (settings) {
+    settings = $.extend({}, drupalSettings.dialog, options, settings);
   // Trigger a global event to allow scripts to bind events to the dialog.
-  $(window).trigger('dialog:beforecreate', [this, options]);
-  this.element.dialog(options);
-  this.isOpen = true;
-  $(window).trigger('dialog:aftercreate', [this, options]);
-}
+    $(window).trigger('dialog:beforecreate', [dialog, $element, settings]);
+    $element.dialog(settings);
+    dialog.open = true;
+    $(window).trigger('dialog:aftercreate', [dialog, $element, settings]);
+  }
 
-Drupal.dialog.prototype.close = function (value) {
-  $(window).trigger('dialog:beforeclose', [this]);
-  Drupal.detachBehaviors(this.element[0], null, 'unload');
-  this.element.dialog('close');
-  this.returnValue = value;
-  this.isOpen = false;
-  $(window).trigger('dialog:afterclose', [this]);
-}
+  function closeDialog (value) {
+    $(window).trigger('dialog:beforeclose', [dialog, $element]);
+    $element.dialog('close');
+    dialog.returnValue = value;
+    dialog.open = false;
+    $(window).trigger('dialog:afterclose', [dialog, $element]);
+  }
 
-/**
- * Binds a listener on dialog creation to handle the cancel link.
- */
-$(window).on('dialog:aftercreate', function (e, dialog, settings) {
-  dialog.element.on('click.dialog', '.dialog-cancel', function (e) {
-    dialog.close('cancel');
-    e.preventDefault();
-    e.stopPropagation();
-  });
-});
+  var undef;
+  var $element = $(element);
+  var dialog = {
+    open: false,
+    returnValue: undef,
+    show: function () {
+      openDialog({modal: false});
+    },
+    showModal: function () {
+      openDialog({modal: true});
+    },
+    close: closeDialog
+};
 
-/**
- * Removes all 'dialog' listeners.
- */
-$(window).on('dialog:beforeclose', function (e, dialog) {
-  dialog.element.off('.dialog');
-});
+  return dialog;
+};
 
 })(jQuery, Drupal, drupalSettings);
diff --git a/core/modules/system/system.module b/core/modules/system/system.module
index a9ee89a..fe54561 100644
--- a/core/modules/system/system.module
+++ b/core/modules/system/system.module
@@ -1242,6 +1242,7 @@ function system_library_info() {
       array('system', 'drupal'),
       array('system', 'drupalSettings'),
       array('system', 'drupal.progress'),
+      array('system', 'jquery.once'),
     ),
   );
 
@@ -1313,6 +1314,9 @@ function system_library_info() {
       'core/misc/dialog.ajax.js' => array('group' => JS_LIBRARY, 'weight' => 3),
     ),
     'dependencies' => array(
+      array('system', 'jquery'),
+      array('system', 'drupal'),
+      array('system', 'drupalSettings'),
       array('system', 'drupal.ajax'),
       array('system', 'drupal.dialog'),
     ),