Well, I haven't managed to get that DJ Native swing project set up on Ubuntu, but sometime ago I played around with the commercial WebRenderer embedded component. I played with it some more and ended up with something that seems to be what dabar asked for. First, as in the visualizer shown yesterday, you choose a menu item called "Visualize", in an HTML file:
And then it's opened in the IDE, using the embedded WebRenderer component:
The scenario above is totally different to the one from yesterday, because here the Visual Library API isn't used at all. Still, if you're going to visualize an HTML file, the above is probably the most useful way of doing so. Go here in the NetBeans Wiki if you want to see how seriously Sun is talking about getting an embedded component into NetBeans IDE.
By the way, the above is the Connecting to a MySQL Database tutorial, which I cannot recommend highly enough.