function spawn(url, width, height)
{
  x = 100, y = 100; // default values

  win = window.open(url, 'popup', 'width='+width+',height='+height+',top='+y+',left='+x+',ScreenX='+x+',ScreenY='+y+',toolbar=0,menubar=0,status=0,location=0');
}