var extMenu = new Array("id1", "id2", "id22", "id23");

function show(object)
{
	if (document.getElementById)
	{
		document.getElementById(object).style.visibility = 'visible';
		document.getElementById(object).style.display = 'block';
	}
	else if (document.layers && document.layers[object])
	{
		document.layers[object].visibility = 'show';
	}
	else if (document.all)
	{
		document.all[object].style.visibility = 'visible';
	}
}

// Hides layers that are visible.
function hide(object)
{
	if (document.getElementById){
		if (object=='all'){
			for (i = 0; i < 4; i++)  
			{document.getElementById(extMenu[i]).style.visibility = 'hidden';}
		}
		else 
			document.getElementById(object).style.visibility = 'hidden';
	}
	else if (document.layers && document.layers[object]){
		if (object=='all'){
			for (i = 0; i < 4; i++)  
				{document.layers[extMenu[i]].visibility = 'hidden';}				
			}			
		else 	
			document.layers[object].visibility = 'hidden';
	}
	else if (document.all){	
		if (object=='all'){
			for (i = 0; i < 4; i++)  
				{document.all[extMenu[i]].style.visibility = 'hidden';}				
			}			
		else 		
			document.all[object].style.visibility = 'hidden';
	}
}