function openWindow(url, w, h)
 {
    var padding;
    padding = 0;

    var screenw = screen.availWidth;
    var screenh = screen.availHeight;
    var winw = (w  + padding);
    var winh = (h  + padding);
    var posx = (screenw / 2) - (winw / 2);
    var posy = (screenh / 3) - (winh / 2);

    var mywin = window.open(url,"mywin","top="+posy+",left="+posx+",width="+winw+",height="+winh+",toolbar=no,locationbar=no,directories=no,statusbar=no,menubar=no,scrollbars=no,resizable=yes,copyhistory=no");

 }