is valid?      

Text formatted with Texy:

Generated HTML code:

<div><a title="obrázek" class="thickbox"
href="/images/img.php?img=obrazek.jpg&amp;type=png&amp;size=800"><img
src="/images/img.php?img=obrazek.jpg&amp;type=jpg&amp;size=300"
alt=""></a></div>

Verze Texy: 3.2.3 (konfigurace)