Click the Action button to get the Mandelbrot outline. Then use the mouse button to mark a spot as the reference point for a Julia set. The next click on the Action button will generate the Julia set boundary for the selected point.
You should have seen that Julia sets generated from inside the Mandelbrot set are those that are open loops. Those from well outside the set are separate islands. Those from the boundary tend to share the characteristics of the Mandelbrot set in the region from which they were generated.