Is it possible that the hype HTML(injected into an iframe) could scan up the HTML tree and and checked of the Master-HTML DOM ist parsed?
But I think that is impossible, therefore a build in timeout event would be good. But this we can generate ourselves via a js function.
This falls under the sandbox security. You can communicate via postMessage but this is mostly not possible if you don’t control the host document. Hence ad server do have access to both ends of the equation and therefore often offer support for syncing wallpaper ads made up of multiple slots and offer other “communication” means. Update: double post removed Duo to connectivity problems