function getStrecthbox(){
	var leftbox_h = getObject("leftbox").offsetHeight;
	var mainbox_h = getObject("mainbox").offsetHeight;
	var difi = leftbox_h - mainbox_h;
	
	if(difi > 0){
		if(getObject("strecthbox") != null){
				var strecth_h = getObject("strecthbox").offsetHeight; //azert kell mert ie csalhat a tartalom miatt...
				getObject("strecthbox").style.height = difi + strecth_h + "px";
		}
	} else if(difi < 0){
		getObject("leftbox").style.height = leftbox_h + Math.abs(difi) + "px";
	}
}

function getObject(obj){
	return document.getElementById(obj);
}