Image if not in Fullscreen

Is there any way in javascript, if the course is not full screen, a layer that is hidden appears? I want to make full screen mandatory

ActivePresenter
windows 7

Hi,

You can add the following script to slide On Load event

function fullscreenHandler() {
    var hiddenObject = prez.object('object name');
    if (AP.fullscreen.fullscreenElement())  // in fullscreen mode
        hiddenObject.hide();
    else
        hiddenObject.show();
}
fullscreenHandler();
AP.fullscreen.addEventListener('fullscreenchange', fullscreenHandler, false);

Regards