The HTML Editor supports HTML5, the most current (and most powerful) standard in web design, but Internet Explorer 7 doesn't support code this advanced. If you've been using the same code for years, IE7 should render everything just fine, but newer versions of IE will render that same code just as well.
Therefore, we've included the ability to switch between several versions of Internet Explorer to use for internal preview.
http://www.coffeecup.com/files/images/preview-uses.png
If anyone is interested in trying this new version out before it is released, drop me an e-mail at scott@coffeecup.com