var lastShownSubNav = "subnav_blank";
function showSubNav(elementId)
{
	hideElement = document.getElementById(lastShownSubNav);
	showElement = document.getElementById(elementId);

	if (hideElement != null)
	{
		hideElement.style.visibility = "hidden";
	}

	if (showElement != null)
	{
		showElement.style.visibility = "visible";
		lastShownSubNav = elementId;
	}
	//document.getElementById(elementId).style.visibility = "visible";
}