How To Detect That User Closes The User-agent Window ?

I have read all posts about how to detect that url have changed to new
page and trigger the event handler then eg.

function aidLogout(evt) {
if(evt) {
/* maybe via analyse of evt object i can detect the close of the
browser window */
}
if(window.event) {
/* maybe via analyse of window.event object i can detect the close of
the browser window */
}
var i = new Image();
i.src = "aidlogout.asp?uid=1562&SessionID=ABCDEFGHIJKLMNOP"
} /* assuming that aidlogout.asp will return nothing or empty image */

window.unload = aidLogout;
/* or via
if(window.addEventListener) {
window.addEventListener("unload", aidLogout, false);
} else
if(window.attachEvent) {
window.attachEvent("unload", aidLogout);
}

PS i know about super Gecko onclose event which fires when browser
window is closed, but i could not find such method in IE.