The IFE often has map data on it, showing position, altitude, speed, distance to destination, etc. I wonder whether it comes from an independent GPS, or from avionics? I seem to recall that on past flights, the heading at the gate was correct (also while being towed in reverse), which tends to indicate this does not come from GPS. So maybe there is a connection between avionics and IFE? Hopefully, it is a very unidirectional connection!