After a little turkey coma and basking in a Packers win, I decided to open the door to the push and pop routines. Basically, the push_group() routine pushes a drawing activity onto the drawing stack, and pop_group() pulls it off – creating a pattern-surface as a result. This can be dropped into an image and used over and over.
In this case, you see that when the system calls the paint() routine, it will reuse the existing image, but if I bang the JSUI object, it will recreate a new image. This is the sort of thing that you will have to do if you choose to reuse a display.