var tabArr = null;
var selectedTab = 0;
var showItemCount = 2;
var steps = 1;

function scrollTabnav(direction) {
	if ( tabArr == null )
		tabArr = $('contenttabs').childNodes;

	selectedTab += direction * steps;

	if(selectedTab < 0)
		selectedTab = 0;
	else if(selectedTab > (tabArr.length - showItemCount))
		selectedTab = tabArr.length - showItemCount;

	setInvisible();
	for(var i = selectedTab; i < selectedTab + showItemCount; i++) {
		if(tabArr[i]) {
			tabArr[i].removeClassName('hidden');
			tabArr[i].addClassName('visible');
		}
	}
}

function setInvisible() {
	for(i = 0; i < tabArr.length; i++) {
		tabArr[i].removeClassName('visible');
		tabArr[i].addClassName('hidden');
	}
}