- Apparently _content works everywhere in Mozilla.  Maybe this should go into
TDEHTMLPart afterall.  That would solve the form post problem too.
- Forms don't work.  I don't know if they will for a long time since we can't
  really filter them with TDEHTML.
- Allow setting the useragent (only do this in a clean fashion!!)
- Double check the TDEHTML extensions for security implications.