var ALERT_TITLE = "ERROR";
var ALERT_BUTTON_TEXT = "Continue";

if(document.getElementById) {
window.alert = function(txt) {
createCustomAlert(txt);
}
}

function createCustomAlert(txt) {
d = document;

if(d.getElementById("modalContainer")) return;

mObj = d.getElementsByTagName("body")[0].appendChild(d.createElement("div"));
mObj.id = "modalContainer";
mObj.style.height = d.documentElement.scrollHeight + "px";

alertObj = mObj.appendChild(d.createElement("div"));
alertObj.id = "alertBox";
if(d.all && !window.opera) alertObj.style.top = document.documentElement.scrollTop + "px";
alertObj.style.left = (d.documentElement.scrollWidth - alertObj.offsetWidth)/2 + "px";
alertObj.style.visiblity="visible";

h1 = alertObj.appendChild(d.createElement("h1"));
h1.appendChild(d.createTextNode(ALERT_TITLE));

msg = alertObj.appendChild(d.createElement("p"));
msg.appendChild(d.createTextNode(txt));

btn = alertObj.appendChild(d.createElement("a"));
btn.id = "closeBtn";
btn.appendChild(d.createTextNode(ALERT_BUTTON_TEXT));
btn.href = "#";
btn.onclick = function() { removeCustomAlert();return false; }


}

function removeCustomAlert() {
document.getElementsByTagName("body")[0].removeChild(document.getElementById("modalContainer"));
}