function expand_collapse_parent(child_obj) {
    expand_collapse(child_obj.parentNode);
}
function expand_collapse(dom_obj) {
    /* Expand or Collapse any DOM object - usually a list or a div
       The object must contain an image tag, showing the expanded / collapsed state of the object.
       Typically triggered by onclick="expand_collapse_parent(this);" event handler on the image tag.
       Really just sets the parent object's class to 'expanded' or 'collapsed' - CSS does the rest.
     */
    var img_obj = dom_obj.getElementsByTagName('img')[0];
    var css_class = dom_obj.className;

    if (css_class.search(/collapsed/g) > -1) {
        img_obj.src = "/media/static/images/collapse.png";
        img_obj.title = "collapse";
        img_obj.className = "collapse";
        img_obj.alt = '-';
        dom_obj.className = css_class.replace(/collapsed/g, 'expanded');
    }
    else {
        img_obj.src = "/media/static/images/expand.png";
        img_obj.title = "expand";
        img_obj.className = "expand";
        img_obj.alt = '+';
        if (css_class.search(/expanded/g) > -1) {
            dom_obj.className = css_class.replace(/expanded/g, 'collapsed');
        }
        else {
            dom_obj.className = css_class + ' collapsed';        
        }
    }
}