I've got a java app running on a 9210i in which I have one frame class, and multiple panel classes which are instantiated during runtime and applied to the frame, giving me multiple forms. Im not sure if this is the most appropriate way of doing this, but it seems to work.
Except for one thing
When you change panels (with the nokia command buttons) focus is lost, so you can no longer input text, etc into the components on the panel. I've tried requestfocus() on the panel, frame and textbox but it doesn't seem to make a difference.