var newWin = null; 
function popUp(strURL, strType, strWidth, strHeight) { 
  var winX = (screen.width - strWidth) / 2;
  var winY = (screen.height - strHeight) / 2;
  var strOptions=""; 
  if (strType=="fixed") 
    strOptions="resizable=0,menubar=1,toolbar=0,scrollbars=1,status=0,height="+strHeight+",width="+strWidth+",left="+winX+",top="+winY;
  if (strType=="flex") 
  strOptions="resizable=1,menubar=1,toolbar=0,scrollbars=1,status=0,height="+strHeight+",width="+strWidth+",left="+winX+",top="+winY;
  newWin = window.open(strURL, 'newWin', strOptions); 
}