Element.extend({
	isVisible: function() {
		return this.getStyle('display') != 'none';
	},
	toggle: function() {
		return this[this.isVisible() ? 'hide' : 'show']();
	},
	hide: function() {
		this.originalDisplay = this.getStyle('display'); 
		this.setStyle('display','none');
		return this;
	},
	show: function(display) {
		this.originalDisplay = (this.originalDisplay=="none")?'block':this.originalDisplay;
		this.setStyle('display',(display || this.originalDisplay || 'block'));
		return this;
	}
});