Jarda contributed a new sample to
contrib, called
manifesteditor. If you're looking to find out about
MultiView editors, I highly recommend it. (I discovered I needed a trunk build, together with JDK 1.6, but haven't yet worked out why, and maybe it isn't true.) It's a pretty good sample that will form the basis of a chapter in the upcoming module development book. It has a normal text editor for Manifest files, with a "Visual mode" that consists of a property sheet. It isn't hard to adapt it to your own purposes. I put lots of
JOptionPane.showMessageDialog lines in a variety of methods, to see what gets called when. At the end of it all, I created the start of a very simple WYSIWYG editor for HTML files. This is the visual part:

And when you click "Text", you see the textual side of the story:

I'd like to use Jarda's sample as the basis of a tutorial too, so that the many people waiting for information in this subject don't have to wait all the way to half way next year, which is when the book is set to be released... But, if you can't wait, check out contrib/manifesteditor, and just play with the code like I did.
P.S. Don't you ever sleep?