function openWin(page, width, height, winname)
{
  var url = page + ".htm";

  LeftPosition = (screen.width) ? (screen.width-(parseInt(width)))/2 : 0;
  TopPosition = (screen.height) ? (screen.height-(parseInt(height)))/2 : 0;

  var options = "location=no";
  options += ",menubar=no";
  options += ",scrollbars=yes";
  options += ",resizable=yes";
  options += ",top=" +TopPosition;
  options += ",left="+LeftPosition;
  options += ",width=" + width;
  options += ",height=" + height;
  
  popupWin=window.open(url,winname, options)
}