function popup(mypage) {

var w="780"
var h="470"

var winl = (screen.width - w) / 2;
var wint = (screen.height - h) / 2;
winprops = 'height='+h+',width='+w+',top='+wint+',left='+winl+',resizable=no,status=no'
win = window.open(mypage,'Map',winprops)
if (parseInt(navigator.appVersion) >= 4) { win.window.focus(); }
}