function openNewWin(url, w, h){
    w = w || 750; 
    h = h || 600; 
    var winl = (screen.width - w) / 2;
    var wint = (screen.height - h) / 2;
    myWindow = window.open(url,'NewWin','width='+w+',height='+h+',top='+wint+',left='+winl+',scrollbars=no,resizable=no');
    myWindow.focus();
}