This dialog can be used to change a user's name, password and his permissions. The dialog looks like this:
You can add pages that the user shall not be allowed to access in the "Block access to the following pages" listview. Additionally, you can fine-tune the user's permissions using the checkboxes below the listview.
Note that you cannot change any permissions for the admin user. The admin user is a privileged user that cannot be given any restrictions.