var isDOM = document.getElementById ? true : false;
var isLoaded = false;
var currentNavImage = null;

function init() {
  isLoaded = true;
}

function roll(imgName, imgObj) {
  if (isDOM && isLoaded && (imgName != currentNavImage)) {
    document.getElementById(imgName).src = "/images/" + imgObj + ".gif";
  }
}

function click(imgName, imgObj) {
  if (isDOM && isLoaded && (imgName != currentNavImage)) {
    currentNavImage = imgName;
    document.getElementById(imgName).src = "/images/" + imgObj + ".gif";
  }
}

function check(obj, value, active) {
  if (active) { 
    if (obj.value == value) { 
      obj.value = ''; 
    }
  } 
  else  { 
    if (obj.value == '') { 
      obj.value = value; 
    } 
  }
}