Also in Lesson 23 of the Tutorial.
You can disable the Edit Script menu item under Settings>Document Settins>Security.
The problem is that any User can use the same menu command to enable the Edit Script.
This is because all users have "ADMIN" access rights as default.
You need to create users with "USER" access level. These users cannot access the Security pages.
This can be done in the script, by defining the users and their privileges in an access section of the script ie section beginning with Section Access;
Never tried to block an object, but i am sure it is all in there.