(function ($) {

Drupal.behaviors.menuChangeParentItems = {

  attach: function (context, settings) {

    $('fieldset#edit-menu input').each(function () {

      $(this).change(function () {

        // Update list of available parent menu items.

        Drupal.menu_update_parent_list();

      });

    });

  }

};

/**

 * Function to set the options of the menu parent item dropdown.

 */

Drupal.menu_update_parent_list = function () {

  var values = [];

  $('input:checked', $('fieldset#edit-menu')).each(function () {

    // Get the names of all checked menus.

    values.push(Drupal.checkPlain($.trim($(this).val())));

  });

  var url = Drupal.settings.basePath + 'admin/structure/menu/parents';

  $.ajax({

    url: location.protocol + '//' + location.host + url,

    type: 'POST',

    data: {'menus[]' : values},

    dataType: 'json',

    success: function (options) {

      // Save key of last selected element.

      var selected = $('fieldset#edit-menu #edit-menu-parent :selected').val();

      // Remove all exisiting options from dropdown.

      $('fieldset#edit-menu #edit-menu-parent').children().remove();

      // Add new options to dropdown.

      jQuery.each(options, function(index, value) {

        $('fieldset#edit-menu #edit-menu-parent').append(

          $('<option ' + (index == selected ? ' selected="selected"' : '') + '></option>').val(index).text(value)

        );

      });

    }

  });

};

})(jQuery);