function openWin(url, windowname, width, height)
{
  xPos = (screen.width - width) / 2
  yPos = (screen.height - height) / 2
  window.open(url, windowname, 'width=' + width + ',height=' + height + ',!scrollbars,!menubar,resizable,!status,left=' + xPos + ',top=' + yPos)
  return true;
}