Use (Esc) to escape the fullscreen mode.
A true fullscreen mode ! Without Flash ! So yeah, I turned it into a WordPress Plugin.
It’s quite experimental so far, but “support is coming to most browsers in the next few months”. You should read John Dyer’s post about that.
[fullscreen target="#have-you-seen-this-dog" text="See the fullscreen dog"]
The plugin come with a widget and a shortcode to generate the button. Use a CSS selector to target the element you want to display in fullscreen, and that’s it.
Enjoy folks !