//last_tab = 'tab1';
function show_next(tab_name)
{
	document.getElementById(last_tab).className = last_tab+'rollover';
	document.getElementById(tab_name).className = tab_name+'active';
	
	
	hide(last_tab+'_content');
	show(tab_name+'_content');
	
	last_tab = tab_name;
}

function show(layerName) {
document.getElementById(layerName).style.display = 'block';
document.getElementById(layerName).style.visibility = 'visible';
}

function hide(layerName) {
document.getElementById(layerName).style.display = 'none';
document.getElementById(layerName).style.visibility = 'hidden';
}