...it is now also possible to map databases to colors:
And, as I had hoped, I was able to completely remove all the db-related code (especially connection dialogs) from the original application. That's already three less packages than before, because the NetBeans Database Explorer now performs the same functionality as all those small custom dialogs.
The next area to attack is the progress monitoring functionality. A lot of it shouldn't be needed anymore, since the NetBeans Platform has its own progress bar. That means that at least the JFrame of the original application for showing progress (and cancelling it, etc) during the db connection should be removable, too.
Onwards to a really slimmed down application!