// Retourne à l'action précédente
function changeLastHistory(arg) {

	var file = "ajax/changeLastHistory.php";	// renvoie le dernier "changeContents"

	//alert("changeHistory");

	var xhr_object = null;
    xhr_object = new XMLHttpRequest();
	xhr_object.open("POST", file, true);
    xhr_object.onreadystatechange = function() {
		if (xhr_object.readyState == 4) {
			if ( xhr_object.responseText !="") {
				//alert(xhr_object.responseText);				
				eval(xhr_object.responseText);  // on évalue direct l'expression...
			}
		}
    }
	xhr_object.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
	xhr_object.send(arg);
}