function set_div (id, new_display) {

	var el = document.getElementById(id);
	
	if (el) {
	
		if (!new_display) {
			
			var display = el.style.display;
			
			if (display == 'block') {
				
				var new_display = 'none';
				
			} else {
				
				var new_display = 'block';
			}
		}
		
		el.style.display = new_display;
	}
}