yeni = null;
function popup (a, b, c) 
{
  var en = (b == 0) ? 300 : ((b < 200) ? 200 : ((b > 600) ? 600 : b));
  var boy = (c == 0) ? 400 : ((c < 300) ? 300 : ((c > 400) ? 400 : c));

  if (yeni == null || yeni.closed) 
  {
yeni=window.open(a,"outputWindow","menubar=yes,scrollbars=yes,resizable=yes,width="+en+",height="+boy);
  } 
  else 
  {
    window.yeni.location=a;
  }
  if (navigator.appName == "Microsoft Internet Explorer" &&
    parseInt (navigator.appVersion) >= 4) 
  {
    yeni.focus();
  } 
  else 
  {
    if(navigator.appName != "Microsoft Internet Explorer")
    yeni.focus(); 
  }
}