Inviz

	getFirst: function(){		return this.walk(0, 'first');	},	getLast: function(){		return this.walk(1, 'last');	},		getPrevious: function(){		return this.walk(1);	},		getNext: function(){		return this.walk()	},		walk: function(prev, child) {		var el = child ? this[child + 'Child'] : this;		do el = el[(prev ? 'previous' : 'next') +  Sibling]; while($type(el) != 'element');		return $(el);	},