/* handle submenu */ 
function sub(obj) {
	var container = document.getElementById("submenu")
	var children = container.getElementsByTagName("span");
	for ($i=0;$i<children.length;$i++){
		if(children[$i].id == obj){
			children[$i].style.display = 'block';
		}else{
			children[$i].style.display = 'none';
		}
	}
}