function showsub(id) {
		
	mainmenu_id = "mainmenu_" + id;
	submenu_id = "submenu_" + id;
	
	document.getElementById("mainmenu_welkom").className = '';
	document.getElementById("mainmenu_diensten").className = '';
	document.getElementById("mainmenu_portfolio").className = '';
	document.getElementById("mainmenu_nieuws").className = '';
	document.getElementById("mainmenu_contact").className = '';
	//document.getElementById("mainmenu_tools").className = '';
	//document.getElementById("mainmenu_contact").className = '';
	//document.getElementById("mainmenu_registreren").className = '';
	
	document.getElementById(mainmenu_id).className = 'active';
		
	document.getElementById("submenu_welkom").style.display = 'none';
	document.getElementById("submenu_diensten").style.display = 'none';
	document.getElementById("submenu_portfolio").style.display = 'none';
	document.getElementById("submenu_nieuws").style.display = 'none';
	document.getElementById("submenu_contact").style.display = 'none';
	//document.getElementById("submenu_tools").style.display = 'none';
	//document.getElementById("submenu_contact").style.display = 'none';
	//document.getElementById("submenu_registreren").style.display = 'none';
	
	document.getElementById(submenu_id).style.display = 'block';
}