function window_open(url,name,w,h)
{
  w+=32;
  h+=96;
  wleft=(screen.width-w)/2;
  wtop=(screen.height-h)/2;
  if (wleft<0) {
    w=screen.width;
    wleft=0;
  }
  if (wtop<0) {
    h=screen.height;
    wtop=0;
  }
  var win=window.open(url,
    name,
    'width='+w+', height='+h+', '+
    'left='+wleft+', top='+wtop+', '+
    'location=no, menubar=no, '+
    'status=no, toolbar=no, scrollbars=yes, resizable=no');
  win.resizeTo(w, h);
  win.moveTo(wleft, wtop);
  win.focus();
}