//permet de contrôler les événements
function addLoadListener(func) {
   if (window.addEventListener) {
      window.addEventListener("load", func, false);
   } else if (document.addEventListener) {
      document.addEventListener("load", func, false);
   } else if (window.attachEvent) {
      window.attachEvent("onload", func);
   }
}
function addUnloadListener(func) {
   if (window.addEventListener) {
      window.addEventListener("unload", func, false);
   } else if (document.addEventListener) {
      document.addEventListener("unload", func, false);
   } else if (window.attachEvent) {
      window.attachEvent("onunload", func);
   }
}