This is broken in version 2.0 (already with the 1.3 series this also was the case).
Looking at the discussions mid last year, i thought better to wait to update my plugins. With version 2.0 i wanted to catch up.
The quick fix (http://mantisbt.org/forums/viewtopic.ph ... ipt#p60035) still works which is fine but this cannot be the way.
In standard mantis now the following line even fails:
<a href="javascript: alert('Hello World')">Click Me</a>

So my question is how I would need to handle this properly, is there some guidance avaiable /