Element.implement({isDisplayed:function(){return this.getStyle("display")!="none"},isVisible:function(){var a=this.offsetWidth,b=this.offsetHeight;return(a==0&&b==0)?false:(a>0&&b>0)?true:this.style.display!="none"},toggle:function(){return this[this.isDisplayed()?"hide":"show"]()},hide:function(){var b;try{b=this.getStyle("display")}catch(a){}if(b=="none"){return this}return this.store("element:_originalDisplay",b||"").setStyle("display","none")},show:function(a){if(!a&&this.isDisplayed()){return this}a=a||this.retrieve("element:_originalDisplay")||"block";return this.setStyle("display",(a=="none")?"block":a)},swapClass:function(a,b){return this.removeClass(a).addClass(b)}});Document.implement({clearSelection:function(){if(window.getSelection){var a=window.getSelection();if(a&&a.removeAllRanges){a.removeAllRanges()}}else{if(document.selection&&document.selection.empty){try{document.selection.empty()}catch(b){}}}}});