This comment to my moan about thisis VERY cool:

I think I've solved your problem! I've successfully developed a Mozilla wrapper for Microsoft's HTC files. It is encapsulated in a single XBL binding, so is exremely portable. The binding is small (4k) and contains compressed JavaScript code which loads the behavior and applies the interface. The interfaces of some objects have been extended to allow further cross-browser compatibility. I've only just finished this development. So you are the first to here about it (apart from a few bored friends). I would be delighted if you would take a look and feed back some comments. For a full working demo (with no browser sniffing), go here: http://dean.edwards.name/my/examples/moz-behaviors/

there is some (scant) documentation here: http://dean.edwards.name/my/ Dean Edwards

Had a quick play with this (I'm off work sick right now so I'm doing this in the few minutes between each extended sleep period), and it looks excellent. I also discovered a cross-browser rich text editor recently...it finally looks like it's becoming possible to support a full rich user experience no matter what browser you're using (there is no excuse so far as I'm concerned to be using Netscape 4.x now...)

UPDATE: Dean continues to update this:

Just a quick note to say that I have since updated this to accomodate Mozilla 1.6b, Also, I will be publishing the full source code for this in a few days time (along with some documentation and coding tips). So check out my site in a few days time.