function toggle_tree(id) {
	element= document.getElementById(id);
    obj= document.getElementById('i_'+ id);
    if (!obj) return;
    
    if (obj.style.display=='visible' || obj.style.display=='block' || obj.style.display=='' ) {
        obj.style.display = 'none';
        if (element.className)
			element.className = "faq_closed";
    }else {
        obj.style.display = 'block';
        if (element.className)
			element.className = "faq_open";
    } 
}