patch - menu_block: allowing 2nd level menu_block not limited to active parent

composer.json

@@ -244,7 +244,8 @@
               "2962965": "https://www.drupal.org/files/issues/2018-09-01/block-permissions-2962965-4.patch"
             },
             "drupal/menu_block": {
-              "2809699": "https://www.drupal.org/files/issues/2018-10-26/menu_block-label_configuration-2809699-82.patch"
+              "2809699": "https://www.drupal.org/files/issues/2018-10-26/menu_block-label_configuration-2809699-82.patch",
+              "2811337": "https://www.drupal.org/files/issues/menu_block-2_level_menu_block_not_limited_to_active_parent-2811337-58.patch"
             },
             "drupal/entity_embed": {
               "2881745": "https://www.drupal.org/files/issues/2018-12-04/2881745-22.patch"

vendor/composer/installed.json

@@ -4636,7 +4636,8 @@
                 }
             },
             "patches_applied": {
-                "2809699": "https://www.drupal.org/files/issues/2018-10-26/menu_block-label_configuration-2809699-82.patch"
+                "2809699": "https://www.drupal.org/files/issues/2018-10-26/menu_block-label_configuration-2809699-82.patch",
+                "2811337": "https://www.drupal.org/files/issues/menu_block-2_level_menu_block_not_limited_to_active_parent-2811337-58.patch"
             }
         },
         "installation-source": "dist",

web/modules/menu_block/src/Plugin/Block/MenuBlock.php

@@ -209,13 +209,36 @@ public function build() {
     if ($depth > 0) {
       $parameters->setMaxDepth(min($level + $depth - 1, $this->menuTree->maxDepth()));
     }
+
+    // For menu blocks with start level greater than 1, only show menu items
+    // from the current active trail. Adjust the root according to the current
+    // position in the menu in order to determine if we can show the subtree.
+    // If we're using a fixed parent item, we'll skip this step.
+    $fixed_parent_menu_link_id = str_replace($menu_name . ':', '', $parent);
+    if ($level > 1 && !$fixed_parent_menu_link_id) {
+      if (count($parameters->activeTrail) >= $level) {
+        // Active trail array is child-first. Reverse it, and pull the new menu
+        // root based on the parent of the configured start level.
+        $menu_trail_ids = array_reverse(array_values($parameters->activeTrail));
+        $menu_root = $menu_trail_ids[$level - 1];
+        $parameters->setRoot($menu_root)->setMinDepth(1);
+        if ($depth > 0) {
+          $max_depth = min($level - 1 + $depth - 1, $this->menuTree->maxDepth());
+          $parameters->setMaxDepth($max_depth);
+        }
+      }
+      else {
+        return array();
+      }
+    }
+
     // If expandedParents is empty, the whole menu tree is built.
     if ($expand) {
       $parameters->expandedParents = array();
     }
     // When a fixed parent item is set, root the menu tree at the given ID.
-    if ($menuLinkID = str_replace($menu_name . ':', '', $parent)) {
-      $parameters->setRoot($menuLinkID);
+    if ($fixed_parent_menu_link_id) {
+      $parameters->setRoot($fixed_parent_menu_link_id);
 
       // If the starting level is 1, we always want the child links to appear,
       // but the requested tree may be empty if the tree does not contain the