Add class on iframed body

Given that "path mode" is lost after a page change (link click, form submission, etc.), and that it can't be stored in session (it would be shared by all windows, even those that are not iframed) , i propose this in order to handle iframed claroline (especially display resources). It prevents from all unwanted elements (top bar, left bar, footer, etc.) from reappering.

If the window is detect in a frame, it adds a class on the body, and this class is used in a css file, to hide some elements and remove some margins and paddings.

it's quite twited but i have not find better yet.