allow full screen in iFrame

Hello,
I create a iFrame gallery. In each iFrame I have a html page with only a webgl based viewer. The viewer allows normally to go in fullscreen. But the fullscreen is only working in the iframe and not on the site (I still see the light box). I would like to have something like youtube full screen who is working very good. I try to put something like “allowfullscreen=true” after the shortcode but it doesn’t work.
Sorry for my english,
Thank you