I’d like to present some photos in a fullscreen slideshow. Is there a way to activate “#hide-content” directly with clicking the menu button of this slideshow? I’ve just tried to put “#hide-content” in the URL-field of the menu but it won’t work.
That’s not easily possible. You could modify the function and use jquery filters and the post/page id class to filter certain pages or use an if statement with the hasClass function but both things require a bit of work (and js skills) on your end.