Target is to enlarge pictures. I am working with js. So I implemented following code:
<code>
<script src="LINK_TO_modal.js" type="text/javascript"></script>
<p><input type="button" id="show" value="Show panel" /></p>
<div id="modalContainer">
<div id="modalPanel">
<div class="hd">Moodle</div>
<div class="bd">Moodle (abbreviation for Modular Object-Oriented Dynamic Learning Environment) is a free and open-source e-learning software platform, also known as a Course Management System, Learning Management System, or Virtual Learning Environment (VLE). As of October 2010 it had a user base of 49,952 registered and verified sites, serving 37 million users in 3.7 million courses. </div>
<div class="ft">[Footer]</div>
</div>
</div>
</code>

Output removes some tags (i.e. input tag, some div definitions; but they are stored in the mysql database).

Same test with i.e. a moodle textpage is working properly.

Before I tried with directly embedded js-code in data form using the js-tab. But I did not get it to work either.