var new_window=0;
function close_window()
{
if (new_window.closed==false) 
  new_window.close()
}
function openWindow(url, w, h, d)
{
if ((new_window!=0) && (!new_window.closed))
{
  close_window();
}
new_window = open(url, 'name', 'width=' + w + ',height=' + h);
new_window.moveTo(200,200);
}