var collapseClass = "expandable";

initToggle = function() {
    if(document.getElementById && document.createTextNode) {
        var entries = $$("." + collapseClass);
        for(i=0;i<entries.length;i++) {
			assignCollapse(entries[i]);
		}
    }
}

assignCollapse = function (entry) {
	var title = entry.firstDescendant(); //uses Prototypes firstDescendant property to find the first element inside each collapsible box
	title.addClassName('toggle'); //adds a class of 'toggle' to all titles
    title.onclick=function(){
		if (entry.hasClassName('collapsed')) {
			entry.addClassName('expanded');
			entry.removeClassName('collapsed');
		}
		else {
			entry.addClassName('collapsed');
			entry.removeClassName('expanded');
		}
		if (entry.hasClassName('open')){
			entry.addClassName('expanded');
			entry.removeClassName('open');
			entry.removeClassName('collapsed');
		}
    };                   
    title.onclick();
}

Event.observe(window, 'load', initToggle, false);