function activate(a){
	var img = document.getElementById(a);
	img.src = "_images/navigation/"+a+".gif";
}

function deactivate(a){
	var img = document.getElementById(a);
	img.src = "_images/navigation/"+a+"_inactive.gif";
}

function showTestimonial(a){
	var div = document.getElementById('testimonial_'+a);
	centerObject(div);
}

function closeTestimonial(a){
	var div = document.getElementById('testimonial_'+a);
	div.style.display = 'none';
}

function centerObject(a){
	a.style.visibility = 'hidden';
	a.style.display  = 'inline';
	var obj = a;
	var w,h;
	if (self.innerHeight) {
		w = self.innerWidth;
		h = self.innerHeight;
		aw = obj.offsetWidth;
		ah = obj.offsetHeight;
	}
	else if (document.documentElement && document.documentElement.clientHeight){
		w = document.documentElement.clientWidth;
		h = document.documentElement.clientHeight;
		aw = obj.clientWidth;
		ah = obj.clientHeight;
	}
	else if (document.body)	{
		w = document.body.clientWidth;
		h = document.body.clientHeight;
		aw = obj.clientWidth;
		ah = obj.clientHeight;
	}
	var atop = (h-ah)/2;
	var aleft = (w-aw)/2;
	obj.style.position = 'absolute';
	obj.style.left = aleft + 'px';
	obj.style.top = atop + 'px';
	obj.style.visibility = "visible";
}