Hello,
I made a few more tests. You have to have user input to go fullscreen (mouse or keyboard).
I'm on a project with keyboard navigation so I made a SWF that will use keypresses to go fullscreen.
It works but... they're a huge drawback : no keyboard input in fullscreen mode !
I tried using : stage.displayState=StageDisplayState.FULL_SCREEN_INTERACTIVE instead of stage.displayState=StageDisplayState.FULL_SCREEN but it's not working once the Flash is imported into Storyline.
I think there should be some kind of authorisation <param name="allowFullScreenInteractive" value="true" />to put in the HTML page somewhere but I don't know where and how.
EDIT :
You have to edit this line as follow in story_content\story.js and it works !
strHtml += "<param name='allowFullScreenInteractive' value='true' />";