diff --git CHANGELOG.txt CHANGELOG.txt
index 28f9c7c..b9408eb 100644
--- CHANGELOG.txt
+++ CHANGELOG.txt
@@ -1,6 +1,7 @@
 Menu Block 7.x-2.x-dev, xxxx-xx-xx (development release)
 ----------------------------------
-- #1017122 by mfer and JohnAlbin: Core bug work-around: add active trail to custom menus
+- #1017142: except for one menu, all other menus (including books) never receive an active trail
+- #1017122 by becw, mfer and JohnAlbin: Core bug work-around: add active trail to custom menus
 - Always show core menu blocks if they are in a region
 - #993998 by tgf: Core menu suppression broken
 - #993998 by jackinloadup: Delete links misplaced on menu list form
diff --git custom_menu_active_trail.inc custom_menu_active_trail.inc
index fbc9bd3..970e247 100644
--- custom_menu_active_trail.inc
+++ custom_menu_active_trail.inc
@@ -2,6 +2,9 @@
 /**
  * @file
  * Add custom menus to the active trail; required to fix Drupal 7.0 core.
+ *
+ * This file WILL be removed after this core bug is fixed: #942782. You have
+ * been warned!
  */
 
 /**
@@ -46,3 +49,142 @@ function _menu_block_add($menu) {
     variable_set('menu_default_active_menus', $active_menus);
   }
 }
+
+/**
+ * Muck with the static cache of menu_link_get_preferred.
+ *
+ * In ensure all menus get an active trail, pre-set the static cache of
+ * menu_link_get_preferred() for the specific menu we want to render.
+ */
+function __menu_block_set_menu_trail($menu_name = FALSE) {
+return;
+  // If there's not menu item, no active trail hack is needed.
+  if (($item = menu_get_item()) && $item == FALSE) {
+    return;
+  }
+
+  $preferred_links = &drupal_static('menu_link_get_preferred');
+  $originals = &drupal_static(__FUNCTION__);
+  $path = $_GET['q'];
+  // Generate a cache ID (cid) specific for this page.
+//  $cid = 'links:' . $menu_name . ':page:' . $item['href'] . ':' . $GLOBALS['language']->language . ':' . (int) $item['access'] . ':0';
+
+  if ($menu_name) {
+    $originals['preferred_link'] = $preferred_links[$path];
+    $originals['active_menus'] = variable_get('menu_default_active_menus', FALSE);
+//    $originals['cache'] = cache_get($cid, 'cache_menu');
+//dsm($originals['cache']);
+
+    $preferred_links[$path] = _menu_link_get_preferred($path, $menu_name);
+    variable_set('menu_default_active_menus', array($menu_name));
+//    cache_clear_all($cid, 'cache_menu');
+if ($menu_name == 'book-toc-359') { dsm('start'); dsm($preferred_links); }
+  }
+  else {
+    $preferred_links[$path] = $originals['preferred_link'];
+    if ($originals['active_menus'] === FALSE) {
+      variable_del('menu_default_active_menus');
+    }
+    else {
+      variable_set('menu_default_active_menus', $originals['active_menus']);
+    }
+//    cache_set($cid, $originals['cache']->data, 'cache_menu');
+dsm('end');
+  }
+}
+
+/**
+ * Lookup the preferred menu link for a given system path.
+ *
+ * @param $path
+ *   The path, for example 'node/5'. The function will find the corresponding
+ *   menu link ('node/5' if it exists, or fallback to 'node/%').
+ * @param $menu_name
+ *   The name of a menu used to restrict the search for a prefered menu link.
+ *   If not specified, all the menus returned by menu_get_active_menu_names()
+ *   will be used.
+ *
+ * @return
+ *   A fully translated menu link, or NULL if not matching menu link was
+ *   found. The most specific menu link ('node/5' preferred over 'node/%') in
+ *   the most preferred menu (as defined by menu_get_active_menu_names()) is
+ *   returned.
+ */
+function _menu_link_get_preferred($path = NULL, $menu_name = '') {
+  $preferred_links = &drupal_static(__FUNCTION__);
+
+  if (!isset($path)) {
+    $path = $_GET['q'];
+  }
+
+  if (!isset($preferred_links[$path][$menu_name])) {
+    $preferred_links[$path][$menu_name] = FALSE;
+
+    // Look for the correct menu link by building a list of candidate paths,
+    // which are ordered by priority (translated hrefs are preferred over
+    // untranslated paths). Afterwards, the most relevant path is picked from
+    // the menus, ordered by menu preference.
+    $item = menu_get_item($path);
+    $path_candidates = array();
+    // 1. The current item href.
+    $path_candidates[$item['href']] = $item['href'];
+    // 2. The tab root href of the current item (if any).
+    if ($item['tab_parent'] && ($tab_root = menu_get_item($item['tab_root_href']))) {
+      $path_candidates[$tab_root['href']] = $tab_root['href'];
+    }
+    // 3. The current item path (with wildcards).
+    $path_candidates[$item['path']] = $item['path'];
+    // 4. The tab root path of the current item (if any).
+    if (!empty($tab_root)) {
+      $path_candidates[$tab_root['path']] = $tab_root['path'];
+    }
+
+    // Retrieve a list of menu names, ordered by preference.
+    if ($menu_name !== '') {
+      $menu_names = array($menu_name);
+    }
+    else {
+      $menu_names = menu_get_active_menu_names();
+    }
+
+    $query = db_select('menu_links', 'ml', array('fetch' => PDO::FETCH_ASSOC));
+    $query->leftJoin('menu_router', 'm', 'm.path = ml.router_path');
+    $query->fields('ml');
+    // Weight must be taken from {menu_links}, not {menu_router}.
+    $query->addField('ml', 'weight', 'link_weight');
+    $query->fields('m');
+    $query->condition('ml.link_path', $path_candidates, 'IN');
+
+    // Sort candidates by link path and menu name.
+    $candidates = array();
+    foreach ($query->execute() as $candidate) {
+      $candidate['weight'] = $candidate['link_weight'];
+      $candidates[$candidate['link_path']][$candidate['menu_name']] = $candidate;
+    }
+
+    // Pick the most specific link, in the most preferred menu.
+    $preferred_link = FALSE;
+    foreach ($path_candidates as $link_path) {
+      if (isset($candidates[$link_path])) {
+        foreach ($menu_names as $menu) {
+          if (!$preferred_links[$path][$menu] && isset($candidates[$link_path][$menu])) {
+            $candidate_item = $candidates[$link_path][$menu];
+            $map = explode('/', $path);
+            _menu_translate($candidate_item, $map);
+            if ($candidate_item['access']) {
+              $preferred_links[$path][$menu] = $candidate_item;
+              if (!$preferred_link) {
+                $preferred_link = $candidate_item;
+              }
+            }
+          }
+        }
+      }
+    }
+    if ($menu_name === '' && $preferred_link) {
+      $preferred_links[$path][$menu_name] = $preferred_link;
+    }
+  }
+
+  return $preferred_links[$path][$menu_name];
+}
diff --git menu_block.module menu_block.module
index bd5221d..2ec32fe 100644
--- menu_block.module
+++ menu_block.module
@@ -249,6 +249,9 @@ function menu_tree_build($config) {
   $menu_names = menu_block_get_all_menus();
   menu_block_set_title(t($menu_names[$config['menu_name']]));
 
+  // @TODO: Remove work-around for core bug #942782.
+  __menu_block_set_menu_trail($config['menu_name']);
+
   if ($config['expanded'] || $config['parent_mlid']) {
     // Get the full, un-pruned tree.
     $tree = menu_tree_all_data($config['menu_name']);
@@ -260,6 +263,9 @@ function menu_tree_build($config) {
     $tree = menu_tree_page_data($config['menu_name']);
   }
 
+  // @TODO: Remove work-around for core bug #942782.
+  __menu_block_set_menu_trail();
+
   // Allow alteration of the tree and config before we begin operations on it.
   drupal_alter('menu_block_tree', $tree, $config);