function newwindow(url)
{
top.name = "main_window";
var popup = window.open(url,"newwindow","toolbar=0,location=0,directories=0,status=0,menubar=0,scrollbars=yes,resizable=0,width=320,height=450");
if( navigator.appName.substring(0,8) == "Netscape" )
{
popup.location = windowurl;
popup.opener = self;
}
}