function get_obj(objectId) {
	if(document.getElementById && document.getElementById(objectId)) {
		return document.getElementById(objectId);
	} else if (document.all && document.all(objectId)) {
		return document.all(objectId);
	} else if (document.layers && document.layers[objectId]) {
		return document.layers[objectId];
	} else {
		return false;
	}
}

function add_class(ptr, new_class){
    var r = new RegExp("(.* |)(" + new_class + ")(| .*)", "g");
    if (!ptr.className.match(r)){
        ptr.className = ptr.className + " " + new_class;
    }
}

function remove_class(ptr, old_class){
    var r = new RegExp("(.* |)(" + old_class + ")(| .*)", "g");
    if (ptr.className.match(r)){
        ptr.className = ptr.className.replace(r, '$1$3');
    }
}