The TuneText is a safe self-containing info medium. Unlike conventional editors, it allows only restricted access to its internal data. Namely, only to the text visible on the screen, not HTML tags.
More important, its original source code NEVER changes!
User's edits are saved outside TuneText as a compact script of changes.

Being a perfectly valid HTML code, TuneText is subject to security restrictions of Web browsers, - their concept of safe Internet browsing. In particular, their standards and measures against viruses.

The appearance of TuneText's source code for content files significantly differs from the format of plain text or HTML file. It's a very advanced JavaScript program.
The content is represented in the form of two separate arrays, - for words and for HTML tags. Moreover, they are in a reverse order!
Although this is done exclusively for the purposes of speed optimization, the resulting code is hard for reading and possible copying:

Optionally, you can also use the Microsoft Script Encoder, which can be downloaded from Microsoft Web site for free.
This utility is designed for encoding scripts. As TuneText transforms HTML content into one big script, you can apply the Script Encoder here. With TuneText Builder, this can be done automatically.
Obviously, the Script Encoder is far from the best in the cryptography industry. Nevertheless, it makes the job, - prevents viewing the source code directly: