/**
* Pops up a new window in the middle of the screen
*/
function popupWindow(mypage, myname, w, h, scroll) {
        var winl = (screen.width - w) / 2;
        var wint = (screen.height - h) / 2;
        winprops = 'height='+h+',width='+w+',top='+wint+',left='+winl+',scrollbars='+scroll+',resizable'
        win = window.open(mypage, myname, winprops)
        if (parseInt(navigator.appVersion) >= 4) { win.window.focus(); }
}