Not really complete yet, but this is what I have so far:
One problem is that I haven't integrated the NetBeans HTML Editor yet, so (as reported yesterday) a few features are missing at the moment, possibly because I'm not using the DialogBinding correctly, so maybe those features could be added without my needing to work with the NetBeans HTML Editor at all. For example, there's no code completion, formatting, or contextual menu, since the above isn't actually the NetBeans HTML Editor, but simply a JEditorPane bound to an HTML file in memory.
A nice feature is that each tab in the multiview window comes from a different module, which could be handy for setting up a modular pricing structure. For example, one tab could be free, while the other could be a commercial tab that the user would plug into the application after having paid for it:
Also, none of the UI modules depend on each other. The "CMSModel" module, which contains the Article object (which has two strings, "title" and "content"), is shared amongst all the other modules. There's another shared module called "CMSArticleContext", which uses Wade's CentralLookup (thanks Toni for the help) for the reason described by Tim (here): "I spent the last couple of days here in New Orleans working with some folks with a similar problem - they are building a CRM application on the NetBeans Platform, and the appropriate context for actions and palettes is the selected Customer - it doesn't matter which window has focus."
In the case of the application above, the context is the Article, while the selection is irrelevant, exactly as in Tim's case.
Bear in mind that it is in a very early state, and still error prone, but, if interested, get it here:
I'll upload the source somewhere sometime soon. Or someone else is welcome to do so.