if (document.images) {
  var defImg = "teachers";

  var studentsoff = new Image();
  studentsoff.src = "/share/i/studentsoff.jpg";
  var studentson = new Image();
  studentson.src = "/share/i/studentson.jpg";
  var parentsoff = new Image();
  parentsoff.src = "/share/i/parentsoff.jpg";
  var parentson = new Image();
  parentson.src = "/share/i/parentson.jpg";
  var teachersoff = new Image();
  teachersoff.src = "/share/i/teachersoff.jpg";
  var teacherson = new Image();
  teacherson.src = "/share/i/teacherson.jpg";
  var administratorsoff = new Image();
  administratorsoff.src = "/share/i/administratorsoff.jpg";
  var administratorson = new Image();
  administratorson.src = "/share/i/administratorson.jpg";
  var boardoff = new Image();
  boardoff.src = "/share/i/boardoff.jpg";
  var boardon = new Image();
  boardon.src = "/share/i/boardon.jpg";
}

function act(imgName) {
  if (document.images)
    document.images[imgName].src = eval(imgName + "on.src");
}

function inact(imgName) {
  if (document.images)
    document.images[imgName].src = eval(imgName + "off.src");
}