var origWidth, origHeight;
if (document.layers) {
origWidth = window.innerWidth; origHeight = window.innerHeight;
window.onresize = function() { 
if (window.innerWidth != origWidth || window.innerHeight != origHeight) history.go(0);
}
}

var layer_encour; // ID du layer visible en cour

function swapLayers(id) {
if (layer_encour) hideLayer(layer_encour);
showLayer(id);
layer_encour = id;
//alert(id);
}

function showLayer(id) {
var layer = getElemRefs(id);
if (layer && layer.css) layer.css.visibility = "visible";
//alert(id);
}

function hideLayer(id) {
var layer = getElemRefs(id);
if (layer && layer.css) layer.css.visibility = "hidden";
//alert(id);
}

function getElemRefs(id) {
var elmt = (document.getElementById)? document.getElementById(id): (document.all)? document.all[id]: (document.layers)? document.layers[id]: null;
if (elmt) elmt.css = (elmt.style)? elmt.style: elmt;
return elmt;
}