var winRef;

function clickBuyPopup(urlStr) {


  //alert(window.screenLeft + " / " + window.innerWidth + " / " + window.document.body.clientWidth);

  posL = window.screenLeft + (window.document.body.clientWidth - 650) / 2;
  posT = window.screenTop + (window.document.body.clientHeight - 500) / 2;

  winProps = 'left=' + posL + ',top=' + posT + ',height=800,width=950,status=no,toolbar=no,menubar=no,location=no,scrollbars=auto,resizable=1' ;
  bolWinRef = (winRef && winRef.closed == false) ? 1 : 0;

  if(bolWinRef) {

    winRef.close();
    winRef = window.open(urlStr, 'clickbuy', winProps, 1);
    winRef.focus();

  } else {
    winRef = window.open(urlStr , 'clickbuy' , winProps , 1);
  }
}