Moodle: site administration navigation tree

Trabla: Moodle: site administration navigation tree

Solving:

1. Classes and interfaces ( classes admin_externalpage, admin_category etc. )  of admin settings are defined in file:
.../moodle/lib/adminlib.php



2. Admin Settings Menu Items definition - .../moodle/admin/settings/ folder

This is first file read by lib/adminlib.php - is used to create categories in correct order
../moodle/admin/settings/top.php



3. "Admin Tool" ( located ../moodle/admin/tool ) plugins can add element into admin tree in settings.php files
e.g.
../moodle/admin/tool/assignmentupgrade/settings.php -> adds  "Assignment upgrade helper"