function menu_highlight(x){
	var y = document.getElementById(x);
	y.className='NavBarSelected';
}
function menu_unhighlight(x){
	var y = document.getElementById(x);
	y.className='NavBarUnselected';
}
function arrow_highlight(x){
	var y = document.getElementById(x);
	y.className='arrow_highlighted';
}
function arrow_unhighlight(x){
	var y = document.getElementById(x);
	y.className='arrow_unhighlighted';
}