var activeNaviImage = null;
var activeSubNaviImage = null;

function hoverOn(imageId) {
	if(imageId != activeNaviImage && imageId != activeSubNaviImage) {swapImage('null',imageId,imageId + "_on");}
}

function hoverOff(imageId) {
	if(imageId != activeNaviImage && imageId != activeSubNaviImage) {swapImage('null',imageId,imageId + "_off");}
}

function setActiveNaviImage(imageId) {
	swapImage('null',imageId,imageId + "_on");
	if(activeNaviImage != null && imageId != activeNaviImage && imageId != activeSubNaviImage) {swapImage('null',activeNaviImage,activeNaviImage + "_off");}
	activeNaviImage=imageId;
}

function setActiveSubNaviImage(imageId){
	swapImage('null',imageId,imageId + "_on");
	if(activeSubNaviImage != null && imageId != activeNaviImage && imageId != activeSubNaviImage) {swapImage('null',activeSubNaviImage,activeSubNaviImage + "_off");}
	activeSubNaviImage=imageId;
}