No third party stuff, just some window.addEventListener(“message”) based light JavaScript inlined in the event sheets. I uploaded the c3p if you want to take a look, but beware, it’s not in the best state :)
Also, running the project in a preview seems to break it, so at the moment the only option is to make a modification, export the HTML5 version and run it on a local server (I use “npx http-server”) or deploy it online.