var oldNavBgElem = null;
var navBgId = "navBg";
var baseNavBgId	= "baseNavBg";
var navTableId = "navTable";

function setBaseNavBg() {
	oldNavBgElem = document.getElementById(baseNavBgId);
	setNavBg(oldNavBgElem);
}
function setNavBg(elem) {
	if(elem) {		
		showNavBg();		
		var rrrr = document.getElementById(navTableId);
		var navBg = document.getElementById(navBgId);		
		navBg.style.left = (elem.offsetLeft + rrrr.offsetLeft - 8) + "px";
		navBg.style.width = (elem.offsetWidth + 16) + "px";
		navBg.style.visibility = "visible";
	} else {
		hideNavBg();
	}
}
function hideNavBg() {
	document.getElementById(navBgId).style.visibility="hidden";
}	
function showNavBg() {
	document.getElementById(navBgId).style.visibility="visible";
}
function resetNavBg() {
	setNavBg(oldNavBgElem);
}