function handler(n)	{
	var o = getElement("menu" + n);
	closeAll();
	o.style.display = (o.style.display != "block") ? 'block' : 'none';
}

function closeAll()	{
	for(var i = 1; i <= 4; i++) {
		var o = getElement("menu" + i);
		if(o != null) {
			getElement("menu" + i).style.display = 'none';
		}
	}
}

function getElement(id)	{
	// geen ns4 (zwak hoor jurriaan :P)
	var obj = null;
	if(document.getElementById)
		obj = document.getElementById(id);
	else if(document.all)
		obj = document.all[id];
	else
		obj = null;

	return obj;
}