Why is the HTML content of Air app editable by users? How to make it fixed

Hi,

This problem doesn't occure in browsers. Here is an example:

I can select stuff, press Del - and delete it:

I can even type garbage in there:

Or go to Edit -> Select All, and delete it all:

How to fix this ? I don't want users to be able to do this kind of stuff...

Thank you in advance,