function displayArticle(id, obj) {
  var target = document.getElementById(id);
  if (target.style.display == 'none' || target.style.display == '') {
    target.style.display = 'block';
    obj.innerHTML = '<img src="img/minus_o.gif">';
  } else {
    target.style.display = 'none';
    obj.innerHTML = '<img src="img/plus_o.gif">';
  }
}
var regOver = new RegExp("^(.+)_o(\.gif)");
var regOut = new RegExp("^(.+)(\.gif)");
function mouseOver(obj) {
  var img = obj.firstChild;
  if (!regOver.test(img.src)) {
    regOut.exec(img.src);
    img.src = RegExp.$1 + "_o" + RegExp.$2;
  }
}
function mouseOut(obj) {
  var img = obj.firstChild;
  if (regOver.test(img.src)) {
    img.src = RegExp.$1 + RegExp.$2;
  }
}