function switch_over(selected){
	var list = document.getElementById("nav_ul").getElementsByTagName('li');
	var blue_line =document.getElementById("blue_line");
	var is_interior=false;
	for(var i=0;i<list.length;i++){
		if(list[i].className!="selectedNav"){
			list[i].className= (selected==i) ? "over" : "";
		}else{
			var is_interior=true;
		}
	}
	if(!is_interior){
	/*	blue_line.style.display=(selected==undefined) ? "none" : "block";*/
	}	
}