function action(){
	if(document.getElementById("hidden").value == "cache"){
		document.getElementById("arrow").href = "#rien";
		document.getElementById("img_arrow").src = "img/img_panneaux/arrow.png";
		document.getElementById("hidden").value = "montre";
	}else{
		document.getElementById("arrow").href = "#imgs";
		document.getElementById("img_arrow").src = "img/img_panneaux/arrow_reverse.png";
		document.getElementById("hidden").value = "cache";
	}
}