Hi,
I hope this is the right place to point this out: but I think that using a $modx->webAlert causes the resulting page to not validate as XHTML. This is because there is no type="text/javascript" in the script tag. Also (and I’m not too sure about this), I thought all inline scripts should be escaped using some CDATA tags...
<script type="text/javascript"><!--//--><![CDATA[//><!--
...
//--><!]]></script>
(I’m just taking this from
http://www.hixie.ch/advocacy/xhtml), in case that are some strings with "<tag>" in, or ampersands or such thing that confuse the xml parser.
In this case I don’t think it matters, but generally I think that if a document is sent as application/xhtml+xml then Firefox may throw a wobbly if there are validation problems.
Tommy T.