that what I am faced with in my project now - A swing tree that is expandable without reloading. i just created virtual objects for all nodes I am interested in and it works fine. Oh, and you do have to have Java plug in.
I too have a Swing tree app where I am swing a object identified as a JavaTree from one pane to the next. Did you create a Virtual Object as Type object? How did you get the object to Drag and Drop? I did not see any methods for the specified Virtual Objects to allow this.