I'm testing the 6.2 build, so I'm tripping over several things. The latest is if you select a font to use. If you do not have text highlighted, the font simply reverts back to the prior selection. Only if text is selected does the change stick. This behavior is reproducible on your demo page, using IE7.
And, I've also generated a number of HTMLFILE Invalid Argument errors doing various things, but I'm trying to get more specifics on the sequence of events to recreate the errors before I pass them along to you.
Thanks again,
David