I successfully used the PNG behaviour hack to make transparent PNG images work effortlessly under Internet Explorer. After working some days on the desigh I decided to finally integrate it in my web application.

To my surprise the behavior didn't work anymore and it took me a fairly long time to find out why. It turns out that Internet Explorer only interpretes .htc files correct when they are served with the 'text/x-component' mime-type. This isn't set up by most servlet containers, so if you intend to use these files make sure to add this to your web.xml file:

<mime-mapping>
    <extension>.htc</extension>
    <mime-type>text/x-component</mime-type>
</mime-mapping>