//john reeve did this

var navTimer = 0;
var delay = 100;
var currentLayer;
var staticLayer;

isNS4 = (document.layers) ? true : false;
isIE4 = (document.all && !document.getElementById) ? true : false;
isIE5 = (document.all && document.getElementById) ? true : false;
isNS6 = (!document.all && document.getElementById) ? true : false;

function toggleLayer (toggleLayerName, toggleSwitch) {
	if (isIE5 || isNS6) {
		eval("document.getElementById('"+ toggleLayerName +"').style.visibility='" + toggleSwitch + "'"); 
	}
	else if (isIE4) {
		eval("document.all['" + toggleLayerName +"'].style.visibility='" + toggleSwitch + "'"); 
	}

	else {
		if (toggleSwitch == "hidden") { toggleSwitch = "hide"; }
		else { toggleSwitch = "show"; }
		eval("document.layers['" + toggleLayerName +"'].visibility='" + toggleSwitch + "'"); 
	}
}

//navOver initiated by mouseOver on nav image
function navOver(layerName) { 
	clearTimeout(navTimer); //clear any leftover timers
	if (currentLayer != null) { // turn off old layer right away if it's on
		toggleLayer(currentLayer,'hidden');
	}
	if (staticLayer != null) { //turn off the static layer if on a subsection
		toggleLayer(staticLayer,'hidden');
	}
	currentLayer = layerName; //remember the old layer for the next round
	toggleLayer(layerName,'visible');
}

//navOut initiated by mouseOut of nav image
function navOut(layerName) {
	offLayer = "turnOff('" + layerName + "');";
	navTimer = setTimeout(offLayer, delay);
}

//subNavOver initiated by mouseOver on subnav layer (resets timer)
function subNavOver(layerName) {
	clearTimeout(navTimer);
}

//turnOff initiated by navOut function
function turnOff(layerName) {
	toggleLayer(layerName,'hidden');
	if (staticLayer != null) {
		toggleLayer(staticLayer,'visible');
	}
}	

function specialNavOver(layerName, ir) {
	navOver(layerName);
	changeImages('irnav_presentations',ir+'irnav_presentations_on');
}
function specialNavOut(layerName, ir) {
	navOut(layerName);
	changeImages('irnav_presentations',ir+'irnav_presentations_off');
}
function specialSubNavOver(layerName, ir) {
	subNavOver(layerName);
	changeImages('irnav_presentations',ir+'irnav_presentations_on');
}