function togglelayer(id)
{
	el = document.getElementById(id);
	img = document.getElementById(id+'_switch');//plus-min image uit dropdown_sitemap
	var display = el.style.display;
	if (!display) display = 'block';// initieel geeft el.style.display niks terug
	else if (display == 'block') display = 'none';
	else display = 'block';
//	alert(display);
	el.style.display = display;
	if (display == 'block') img.src = 'fileadmin/img/icons/minus.gif';
	else img.src = 'fileadmin/img/icons/plus.gif';
}