var PREV = '1';
var FOOTER = '20';

function changeDisplay(id) 
{
	if (PREV) {
		PREV = document.getElementById(PREV);
		PREV.style.display = 'none';
	} 

	PREV = id;

	document.getElementById(PREV).style.display = 'block';
}


function showFooter(id) 
{
	if (FOOTER) {
		FOOTER = document.getElementById(FOOTER);
		FOOTER.style.display = 'none';
	} 

	FOOTER = id;

	document.getElementById(FOOTER).style.display = 'block';
}

function hideFooter(id) 
{
	FOOTER = id;

	document.getElementById(FOOTER).style.display = 'none';
}