function openMenu(nID)
{
	var oElem = document.getElementById('submenu_' + nID + '');
	oElem.className = ((oElem.className == 'off') ? 'on' : 'off');

	var oElem = document.getElementById('menu_' + nID + '');
	oElem.className = ((oElem.className == 'category normal') ? 'category active' : 'category normal');
	
	//Elemente schliessen die nicht aktiv sind
	var aElem = document.getElementsByTagName("div");
	for (var i=0; i<aElem.length; i++)
	{
		if(aElem[i].className == 'on' && aElem[i].id != 'submenu_' + nID + '')
			aElem[i].className = 'off';
	}
	
	//pfeile wegklappen
	var aElem = document.getElementsByName('menu');
	for (var i=0; i<aElem.length; i++)
	{
		if(aElem[i].id != 'menu_' + nID + '')
			aElem[i].className = 'category normal';
	}
}