Adding $_configuration['auto_detect_language_custom_pages'] see BT#8840

custompages/language.php

@@ -51,7 +51,14 @@ if (isset($_REQUEST['language']) && !empty($_REQUEST['language']) && in_array($_
 if (isset($_REQUEST['lang']) && !empty($_REQUEST['lang']) && in_array($_REQUEST['lang'], $available_langs)) {
 	$lang_match = $chamilo_langs[$_REQUEST['lang']];
 }
-$_user['language'] = $lang_match;
+global $_configuration;
+$defaultLanguage = api_get_interface_language();
+if (isset($_configuration['auto_detect_language_custom_pages']) &&
+    $_configuration['auto_detect_language_custom_pages'] == true
+) {
+    $defaultLanguage = $lang_match;
+}
+$_user['language'] = $defaultLanguage;
 
 $_SESSION['user_language_choice'] = $lang_match;
 

main/install/configuration.dist.php

@@ -241,3 +241,5 @@ $_configuration['system_stable']     = NEW_VERSION_STABLE;
 // Display sessions catalog
 // 0 = show only courses; 1 = show only sessions; 2 = show courses and sessions
 //$_configuration['catalog_show_courses_sessions'] = 0;
+// Auto detect language custom pages.
+// $_configuration['auto_detect_language_custom_pages'] = true;