var extWin;

function shift_focus(w_name) {
  var newwin=window.open('', w_name, "toolbar,status,menubar,scrollbars,resizable,width=640,height=480"); 
  newwin.focus();
}

function ExtWindow(extURL) {
  if (extWin == null || extWin.closed ) {
    extWin=window.open(extURL, "ESMAIN", "toolbar,status,menubar,scrollbars,resizable,width=640,height=480,left=0,top=0"); 
  }
  else {
    extWin.location.href = extURL
  }
  extWin.focus();
}