var Scroller=new Class({Implements:[Events,Options],options:{area:20,velocity:1,onChange:function(x,y){this.element.scrollTo(x,y)},fps:50},initialize:function(element,options){this.setOptions(options);this.element=document.id(element);this.docBody=document.id(this.element.getDocument().body);this.listener=(typeOf(this.element)!="element")?this.docBody:this.element;this.timer=null;this.bound={attach:this.attach.bind(this),detach:this.detach.bind(this),getCoords:this.getCoords.bind(this)}},start:function(){this.listener.addEvents({mouseover:this.bound.attach,mouseleave:this.bound.detach});return this},stop:function(){this.listener.removeEvents({mouseover:this.bound.attach,mouseleave:this.bound.detach});this.detach();this.timer=clearInterval(this.timer);return this},attach:function(){this.listener.addEvent("mousemove",this.bound.getCoords)},detach:function(){this.listener.removeEvent("mousemove",this.bound.getCoords);this.timer=clearInterval(this.timer)},getCoords:function(event){this.page=(this.listener.get("tag")=="body")?event.client:event.page;if(!this.timer){this.timer=this.scroll.periodical(Math.round(1000/this.options.fps),this)}},scroll:function(){var size=this.element.getSize(),scroll=this.element.getScroll(),pos=this.element!=this.docBody?this.element.getOffsets():{x:0,y:0},scrollSize=this.element.getScrollSize(),change={x:0,y:0},top=this.options.area.top||this.options.area,bottom=this.options.area.bottom||this.options.area;for(var z in this.page){if(this.page[z]<(top+pos[z])&&scroll[z]!=0){change[z]=(this.page[z]-top-pos[z])*this.options.velocity}else{if(this.page[z]+bottom>(size[z]+pos[z])&&scroll[z]+size[z]!=scrollSize[z]){change[z]=(this.page[z]-size[z]+bottom-pos[z])*this.options.velocity}}change[z]=change[z].round()}if(change.y||change.x){this.fireEvent("change",[scroll.x+change.x,scroll.y+change.y])}}});