var timer=0;
var menuItem;
var currentNode;

function setCurrentNode(n){
	currentNode=n;
}

function openMenu(id){	
	menuAbort();

//hide menu if any is shown
	if(menuItem) {
	menuItem.style.display = 'none';
	}
//show menu
	menuItem=document.getElementById(id);
	menuItem.style.display = 'block';
}

function closeMenu(){
	if(menuItem) {
	menuItem.style.display = 'none';
	moveTopNav(currentNode);
	}
	else{
		moveTopNav(currentNode);
	}
}
//delay before visible menu closes
function delayCloseMenu(){
	timer = setTimeout(closeMenu,500);
}


function menuAbort(){
	if(timer)
	{
		clearTimeout(timer);
		timer = null;
	}
}


function moveTopNav(p) {
/** 
The top navigation tabs are all drawn in a single transparent graphic file. 
When the user mouses over hotspots, this function is called to move the 
position of the transparent graphic so that it appears that a new tab is coming 
to the forefront. Putting all the tab images in one graphic file preloads the  
graphics and aids a smooth mouseover display.

The public site and the employee site use different background images in TopNav since 
their tab sets and widths are different.
*/

var offsetX = -6; // Home's X position is -6px
var offsetY = -3; // The Y position is always -3px

	switch (p){
	case "home":
		offsetX = -6;
		break;
	case "empHome": // employee site tab
		offsetX = -6;
		break;
	case "about":
		offsetX = -806;
		break;
	case "join":
		offsetX = -1606;
		break;
	case "seminar":
		offsetX = -2406;
		break;
	case "partners":
		offsetX = -3206;
		break;
	case "myaccount": // employee site tab
		offsetX = -4881;
		break;
	case "helpdesk": // employee site tab
		offsetX = -3906;
		break;
	case "events": // employee site tab
		offsetX = -2931;
		break;
	case "resources": // employee site tab
		offsetX = -1956;
		break;
	case "admin": // employee site tab
		offsetX = -981;
		break;
	default:
		offsetX = -6;
	}
 
	document.getElementById('topNav').style.backgroundPosition = offsetX + "px " + offsetY + "px";
}


document.onclick = closeMenu;