Fx.Tween=new Class({Extends:Fx.CSS,initialize:function(element,options){this.element=this.subject=$(element);this.parent(options);},set:function(property,now){if(arguments.length==1){now=property;property=this.property||this.options.property;}
this.render(this.element,property,now,this.options.unit);return this;},start:function(property,from,to){if(!this.check(arguments.callee,property,from,to))return this;var args=Array.flatten(arguments);this.property=this.options.property||args.shift();var parsed=this.prepare(this.element,this.property,args);return this.parent(parsed.from,parsed.to);}});Element.Properties.tween={set:function(options){var tween=this.retrieve('tween');if(tween)tween.cancel();return this.eliminate('tween').store('tween:options',$extend({link:'cancel'},options));},get:function(options){if(options||!this.retrieve('tween')){if(options||!this.retrieve('tween:options'))this.set('tween',options);this.store('tween',new Fx.Tween(this,this.retrieve('tween:options')));}
return this.retrieve('tween');}};Element.implement({tween:function(property,from,to){this.get('tween').start(arguments);return this;},fade:function(how){var fade=this.get('tween'),o='opacity',toggle;how=$pick(how,'toggle');switch(how){case'in':fade.start(o,1);break;case'out':fade.start(o,0);break;case'show':fade.set(o,1);break;case'hide':fade.set(o,0);break;case'toggle':var flag=this.retrieve('fade:flag',this.get('opacity')==1);fade.start(o,(flag)?0:1);this.store('fade:flag',!flag);toggle=true;break;default:fade.start(o,arguments);}
if(!toggle)this.eliminate('fade:flag');return this;},highlight:function(start,end){if(!end){end=this.retrieve('highlight:original',this.getStyle('background-color'));end=(end=='transparent')?'#fff':end;}
var tween=this.get('tween');tween.start('background-color',start||'#ffff88',end).chain(function(){this.setStyle('background-color',this.retrieve('highlight:original'));tween.callChain();}.bind(this));return this;}});