var isNav4 = (navigator.appName == "Netscape" && 
    parseInt(navigator.appVersion) == 4);
if (parent == window) {
    // Don't do anything if NN4 is printing frame
    if (!isNav4 || (isNav4 && window.innerWidth != 0)) {
           location.href = "main.html?content=" + escape(location.href);
        }
}