var History=$extend(history,{implement:function(obj){return $extend(this,obj);}});History.implement(new Events($empty));History.implement({state:null,start:function(){if(this.started)return this;this.state=this.getHash();if(Browser.Engine.trident){var iframe=new Element('iframe',{'src':"javascript:''",'styles':{'position':'absolute','top':'-1000px'}}).inject(document.body).contentWindow;var writeState=function(state){iframe.document.write('Moo!');iframe.document.close();};$extend(this,{'$listener':function(state){state=decodeURIComponent(state);if(this.state!=state)this.setHash(state).changeState(state);}.bind(this),'setState':function(state,force){if(this.state!=state||force){if(!force)this.setHash(state).changeState(state,true);writeState(state);} return this;},'trace':function(){var state=this.getHash();if(state!=this.state)writeState(state);}});var check=(function(){if(iframe.document&&iframe.document.body){check=$clear(check);if(!iframe.document.body.innerHTML)this.setState(this.state);}}).periodical(50,this);}else{if(Browser.Engine.presto915){new Element('img',{'src':"javascript:location.href='javascript:History.trace();';",'styles':{'position':'absolute','top':'-1000px'}}).inject(document.body);}} this.trace.periodical(150,this);this.started=true;return this;},changeState:function(state,manual){var stateOld=this.state;this.state=state;this.fireEvent('changed',[state,stateOld,manual]);},trace:function(){var state=this.getHash();if(state!=this.state)this.changeState(state);},getHash:function(){var href=location.href,pos=href.indexOf('#')+1;return(pos)?href.substr(pos):'';},setHash:function(state){location.hash='#'+state;return this;},setState:function(state){if(this.state!==state)this.setHash(state).changeState(state,true);return this;},getState:function(){return this.state;}});