function toggle(target) {
	obj=document.getElementById(target);
	obj.style.visibility=( (obj.style.visibility=='hidden') ? 'visible' : 'hidden');
}
function setVisibility(target, isVisible) {
	obj=document.getElementById(target);
	obj.style.visibility=( (isVisible=='true') ? 'visible' : 'hidden');
}
function setContentVisibility(contentId, isVisible) {
	i=0;
	obj=document.getElementById('content' + String(contentId) + String(i));
	while (!(obj==null)) {
		obj.style.visibility=( (isVisible=='true') ? 'visible' : 'hidden');
		i++;
		obj=document.getElementById('content' + String(contentId) + String(i));
	}
	setNavVisibility(contentId, isVisible);
}
function setNavVisibility(navId, isVisible) {
	i=0;
	obj=document.getElementById('nav' + String(i));
	while (!(obj==null)) {
		if (isVisible=='true') {
			if (!(i==navId)) {
				obj.style.visibility='hidden';
			}
		}
		else {
			obj.style.visibility='visible';
		}
		i++;
		obj=document.getElementById('nav' + String(i));
	}
}