Couldn't you create a "system" or other object and have it own the displays by encapsulation. Then ask it for a display when you need it. If the display exists

Couldn't you create a "system" or other object and have it own the displays by encapsulation. Then ask it for a display when you need it. If the display exists for the duration of a callback then I would think simply passing the display as a borrowed reference to the callback would enough. And if you're gonna use C why not just use unsafe rust?