function showArrow(which) {
	var whicharrow = document.getElementById(which);
	
	if (whicharrow) { 
		whicharrow.style.visibility = "visible";
	}
}


function hideArrows() {
	var theolderarrow = document.getElementById('previousarrow');
	var thenewerarrow = document.getElementById('nextarrow');
	
	if (theolderarrow) { 
		theolderarrow.style.visibility = "hidden";
	}
	
	if (thenewerarrow) { 
		thenewerarrow.style.visibility = "hidden";
	}
}