Cross-window scripting

var newwindow = '';

function popitup(url) {
if (!newwindow.closed && newwindow.location) {
newwindow.location.href = url;
}
else {
newwindow=window.open(url,'name','height=200,width=150');
if (!newwindow.opener) newwindow.opener = self;
}
if (window.focus) {newwindow.focus()}
return false;
}