You can prevent a TreePad document from being changed by making it "read-only".
When you open a TreePad document that is read-only, TreePad will shows the message:
"This file is opened in Read-Only mode."
When a file is 'readonly', all commands for changing (editing) the TreePad file are disabled.
This option is useful for distributing TreePad documents which should be changed only by the author(s) or for documents that are accessed by multiple users.
On how to make a database "read-only", please see the child node "Making a TreePad file read-only"'.