function show(layerName) 
{
	document.getElementById(layerName).style.display = '';
	var head = layerName + 'head';
	if ( document.getElementById(head).className == 'tab last')
		document.getElementById(head).className= 'tab last active';
	else
		document.getElementById(head).className= 'tab active';
	 
}

function hide(layerName) 
{
	 
	document.getElementById(layerName).style.display = 'none';
	var head = layerName + 'head';
	if ( document.getElementById(head).className == 'tab last active')
		document.getElementById(head).className= 'tab last';
	else
		document.getElementById(head).className= 'tab';
}