function timeline_later() {
	//alert('2');
	if (timeline_current > 1) {
		current_div_id = "timeline_screen_" + timeline_current;
		screen_div_id = "timeline_screen_" + (timeline_current - 1);
		
		current_div = document.getElementById(current_div_id);
		screen_div = document.getElementById(screen_div_id);
		
		current_div.style.display = "none";
		screen_div.style.display = "block";
	
		timeline_current = timeline_current - 1;
	
	}
}

function timeline_earlier() {
	//alert('3');
	if (timeline_current < timeline_screens) {
		current_div_id = "timeline_screen_" + timeline_current;
		screen_div_id = "timeline_screen_" + (timeline_current + 1);
		
		current_div = document.getElementById(current_div_id);
		screen_div = document.getElementById(screen_div_id);
		
		current_div.style.display = "none";
		screen_div.style.display = "block";
		
		timeline_current = timeline_current + 1;
	
	}
	
}