Element.implement({isVisible:function(){return(this.getStyle('display')||'none')!='none'&&this.getStyle('visibility')!='hidden';},show:function(){return this.setStyle('display',this.retrieve('display','')).set('opacity',1);},hide:function(visibility){if(!this.retrieve('display')){var display=this.getStyle('display');this.store('display',(display=='none')?'block':display);}
return(visibility)?this.set('opacity',0):this.setStyle('display','none');},toggle:function(visibility){return this[this.isVisible()?'hide':'show'](visibility);}});