function swapLyr(obj,id){
	var sLyrs = document.getElementById("onglets").childNodes;
	var sLyrActiv = document.getElementById(id);											
	var sTabs = document.getElementById("header").getElementsByTagName("LI");
	var sTabsActiv = obj.parentNode;
	for (var i=0; i<sLyrs.length; i++) {
		sLyrs[i].className="blk_off";
	}
	for (var i=0; i<sTabs.length; i++) {
		sTabs[i].className="";
	}
	sLyrActiv.className="blk_on";
	sTabsActiv.className="current";											
}