var header_height;

function action_header() {
	var barre = document.getElementById("barre");
	var btn = document.getElementById("action_btn");
	var entete = document.getElementById("entete");
	var content = document.getElementById("contents");
	var menu = document.getElementById("main_menu");

	if(entete!=null && btn!=null && barre!=null && content!=null) {
		if(header_height==null)
		{header_height = entete.offsetHeight;}
		var top = entete.offsetTop;
		if(top==barre.offsetHeight)
		{top = 0;}
		if(top<0){
			slide_header(entete,btn,content,menu,top,+10);
			if(menu) {menu.style.marginTop = "";}
		}
		else {
			slide_header(entete,btn,content,menu,top,-10);
			if(menu) {menu.style.marginTop = "3px";}
		}
	}
}

function slide_header(entete,btn,content,menu,top,move) {
	var time = 20;
	if((top+move)>0 && move==10) {
		entete.style.top = "0px";
		btn.src = btn_down;
		entete.style.zIndex="1";
	}
	else if((top+move)<-header_height) {
		entete.style.top = "-"+header_height+"px";
		btn.src = btn_up;
		entete.style.visibility="hidden";
	}
	else {
		top += move;
		entete.style.top = top+"px";
		setTimeout(function() {slide_header(entete,btn,content,menu,top,move);},time);
	}
	if(move<0)
	{entete.style.zIndex="-1";}
	else
	{entete.style.visibility="";}
	content.style.top = entete.style.top;
	if(menu) {menu.style.top = entete.style.top;}
}

function start_hide(cpt) {
	var entete = document.getElementById("entete");
	var content = document.getElementById("contents");
	var menu = document.getElementById("main_menu");
	if(entete!=null && content!=null) {
		entete.style.top = "-"+entete.offsetHeight+"px";	
		entete.style.zIndex="-1"
		entete.style.visibility="hidden";
		content.style.top = entete.style.top;
		if(menu) {
			menu.style.top = entete.style.top;
			menu.style.marginTop = "3px";
		}
	}
	else
	{setTimeout(function() {start_hide(cpt+=1);},100);}
}