var fixHeight=function(){
	this.elements=['left','middle','right'];
	this.maxHeight=0;
	this.h=function(id){
		var e=document.getElementById(id);
		if(e){
			return e.clientHeight;
		}else{
			return false;
		}
	}
	this.set=function(){
		var h;
		for(var i in this.elements){
			if((h=this.h(this.elements[i]))===false)return;
			if(h>this.maxHeight)this.maxHeight=h;
		}
		for(i in this.elements){
			document.getElementById(this.elements[i]).style.height=this.maxHeight+'px';
		}
	}
}
window.onload=function(){new fixHeight().set();}