--- /dev/null
+<?php
+
+namespace Drupal\settings_tray\Form;
+
+use Drupal\Component\Plugin\PluginInspectionInterface;
+use Drupal\Core\DependencyInjection\ContainerInjectionInterface;
+use Drupal\Core\Entity\EntityStorageInterface;
+use Drupal\Core\Entity\EntityTypeManagerInterface;
+use Drupal\Core\Form\FormStateInterface;
+use Drupal\Core\Plugin\PluginFormBase;
+use Drupal\Core\Render\Element;
+use Drupal\Core\Routing\RedirectDestinationTrait;
+use Drupal\Core\StringTranslation\StringTranslationTrait;
+use Drupal\Core\StringTranslation\TranslationInterface;
+use Drupal\system\MenuInterface;
+use Symfony\Component\DependencyInjection\ContainerInterface;
+
+/**
+ * The off-canvas form handler for the SystemMenuBlock.
+ *
+ * @see settings_tray_block_alter()
+ *
+ * @internal
+ */
+class SystemMenuOffCanvasForm extends PluginFormBase implements ContainerInjectionInterface {
+
+ use StringTranslationTrait;
+ use RedirectDestinationTrait;
+
+ /**
+ * The plugin.
+ *
+ * @var \Drupal\Core\Block\BlockPluginInterface
+ */
+ protected $plugin;
+
+ /**
+ * The menu entity that the block uses and that will be edited in this form.
+ *
+ * @var \Drupal\system\MenuInterface
+ */
+ protected $menu;
+
+ /**
+ * @var \Drupal\Core\Entity\EntityStorageInterface
+ */
+ protected $menuStorage;
+
+ /**
+ * @var \Drupal\Core\Entity\EntityTypeManagerInterface
+ */
+ protected $entityTypeManager;
+
+ /**
+ * SystemMenuOffCanvasForm constructor.
+ *
+ * @param \Drupal\Core\Entity\EntityStorageInterface $menu_storage
+ * @param \Drupal\Core\Entity\EntityTypeManagerInterface $entity_type_manager
+ * @param \Drupal\Core\StringTranslation\TranslationInterface $string_translation
+ */
+ public function __construct(EntityStorageInterface $menu_storage, EntityTypeManagerInterface $entity_type_manager, TranslationInterface $string_translation) {
+ $this->menuStorage = $menu_storage;
+ $this->entityTypeManager = $entity_type_manager;
+ $this->stringTranslation = $string_translation;
+ }
+
+ /**
+ * {@inheritdoc}
+ */
+ public static function create(ContainerInterface $container) {
+ return new static(
+ $container->get('entity_type.manager')->getStorage('menu'),
+ $container->get('entity_type.manager'),
+ $container->get('string_translation')
+ );
+ }
+
+ /**
+ * {@inheritdoc}
+ */
+ public function buildConfigurationForm(array $form, FormStateInterface $form_state) {
+ $form = $this->plugin->buildConfigurationForm([], $form_state);
+ // Move the menu levels section to the bottom.
+ $form['menu_levels']['#weight'] = 100;
+
+ $form['entity_form'] = [
+ '#type' => 'details',
+ '#title' => $this->t('Edit menu %label', ['%label' => $this->menu->label()]),
+ '#open' => TRUE,
+ '#access' => $this->menu->access('edit'),
+ ];
+ $form['entity_form'] += $this->getEntityForm($this->menu)->buildForm([], $form_state);
+
+ // Print the menu link titles as text instead of a link.
+ if (!empty($form['entity_form']['links']['links'])) {
+ foreach (Element::children($form['entity_form']['links']['links']) as $child) {
+ $title = $form['entity_form']['links']['links'][$child]['title'][1]['#title'];
+ $form['entity_form']['links']['links'][$child]['title'][1] = ['#markup' => $title];
+ }
+ }
+ // Change the header text.
+ $form['entity_form']['links']['links']['#header'][0] = $this->t('Link');
+ $form['entity_form']['links']['links']['#header'][1]['data'] = $this->t('On');
+
+ // Remove the label, ID, description, and buttons from the entity form.
+ unset($form['entity_form']['label'], $form['entity_form']['id'], $form['entity_form']['description'], $form['entity_form']['actions']);
+ // Since the overview form is further nested than expected, update the
+ // #parents. See \Drupal\menu_ui\MenuForm::form().
+ $form_state->set('menu_overview_form_parents', ['settings', 'entity_form', 'links']);
+
+ return $form;
+ }
+
+ /**
+ * {@inheritdoc}
+ */
+ public function validateConfigurationForm(array &$form, FormStateInterface $form_state) {
+ $this->plugin->validateConfigurationForm($form, $form_state);
+ $this->getEntityForm($this->menu)->validateForm($form, $form_state);
+ }
+
+ /**
+ * {@inheritdoc}
+ */
+ public function submitConfigurationForm(array &$form, FormStateInterface $form_state) {
+ $this->plugin->submitConfigurationForm($form, $form_state);
+ $this->getEntityForm($this->menu)->submitForm($form, $form_state);
+ $this->menu->save();
+ }
+
+ /**
+ * Gets the entity form for this menu.
+ *
+ * @param \Drupal\system\MenuInterface $menu
+ * The menu entity.
+ *
+ * @return \Drupal\Core\Entity\EntityFormInterface
+ * The entity form.
+ */
+ protected function getEntityForm(MenuInterface $menu) {
+ $entity_form = $this->entityTypeManager->getFormObject('menu', 'edit');
+ $entity_form->setEntity($menu);
+ return $entity_form;
+ }
+
+ /**
+ * {@inheritdoc}
+ */
+ public function setPlugin(PluginInspectionInterface $plugin) {
+ $this->plugin = $plugin;
+ $this->menu = $this->menuStorage->load($this->plugin->getDerivativeId());
+ }
+
+}