This shows how the simulator screen looks while it is running.  The moon "Trails" feature was turned on for this screen capture and you can see the break in the trails as the moons entered in and out of Jupiter's shadow.  This shows how the program simulates the moons disappearance and re appearance from being eclipsed.  Many commercial programs do not simulate this feature.  You can also see the menu options.  You just press a key while the program is running.