var NN4 = document.layers ? true : false;
var IE4 = document.all ? true : false;
var NN6 = document.implementation ? true : false;
var intIntervalID = -1 ;
menus = new Array("submenu_contact", "submenu_activiteiten", "submenu_richtingen", "submenu_sport");

function display(layerName) 
{

	var objLayer ;
	if (intIntervalID != -1)
	{
		clearInterval (intIntervalID) ;
	}
	
	for(i=0; i < menus.length; i++) {
	
		if (IE4) 
		{
			
			objLayer = document.all[layerName].style ;
		    if (menus[i] == layerName)
				objLayer.visibility = "visible";
			else {
				objLayer = document.all[menus[i]].style;
				objLayer.visibility = "hidden";
			}
		}
	
		if(NN4) 
		{
			objLayer = document.layers[layerName] ;
		    if (menus[i] == layerName)
		    	objLayer.visibility = "show";
			else {
				objLayer = document.layers[menus[i]];
		    	objLayer.visibility = "hidden";
			}
		}
		
		if(NN6)
		{
			objLayer = document.getElementById(layerName);
		    if (menus[i] == layerName)
		    	objLayer.style.visibility = "visible";
			else {
				objLayer = document.getElementById(menus[i]);
		    	objLayer.style.visibility = "hidden";
			}
		}
		
	}
}

function hideall(layerN)
{
	var objLayer ;
	var layerName = layerN ;
	
	if (IE4) 
	{
		document.all[layerName].style.visibility = "hidden";							
	}
	if(NN4) 
	{
		document.layers[layerName].visibility = "hidden";
	}
	if(NN6)
	{
		objLayer = document.getElementById(layerName) ;
		objLayer.style.visibility = "hidden";
	}
	return false;
}

function hide(layerName)
{
	intIntervalID = setInterval ("hideall('" + layerName + "')", 1000);
}