Part 1 (removed "st" unit files)

1. in Admin Console:
   • go to Website & Content → Browse Website section
   • click on Content Mode button in top frame
   • confirm, that:
     • green Section Properties button is now shown
     • orange Edit Content button is now shown
     • no error/exception happened
   • click on Section Properties button
   • confirm, that editing window was opened
   • go to Website & Content → Structure & Data section
   • click on Sections tab
   • confirm, that categories were shown

Part 2 (class locator)

1. in IDE create /locator_test.php file with following content:

<?php

/** @var callable $locator */
$locator = require 'tools/class_locator.php';

echo 'In-Portal: ' . $locator('kPlainUrlProcessor') . PHP_EOL;
echo 'Composer: ' . $locator('\QATools\QATools\PageObject\Page') . PHP_EOL;
echo 'Missing: ' . $locator('UnknownClass') . PHP_EOL;

2. run php locator_test.php file from command line
3. confirm, that output was following (replace ... with absolute path to In-Portal):

In-Portal: .../core/kernel/managers/plain_url_processor.php
Composer: .../vendor/qa-tools/qa-tools/library/QATools/QATools/PageObject/Page.php
Missing: