// Doivantuan
function showElement(layer,image){
var myLayer = document.getElementById(layer);
var myImage = document.getElementById(image);
if(myLayer.style.display=="none"){
myImage.src="images/tru.gif";
myLayer.style.display="block";
myLayer.backgroundPosition="top";
} else {
myLayer.style.display="none";
myImage.src="images/cong.gif";
}
}

//tooltip for register
function pw() {
	return window.innerWidth || document.documentElement.clientWidth || document.body.clientWidth;
	} 
function ph() {
	return window.innerHeight || document.documentElement.clientHeight || document.body.clientHeight;
	} 
	
function obH(oi) {
	var obj = document.getElementById(oi); return obj.offsetHeight || obj.clip.height || 0;
	} 
function mX(evt) {
	return evt.clientX ? evt.clientX + (document.documentElement.scrollLeft || document.body.scrollLeft) : evt.pageX;
	} 
	
function mY(evt) {
		return evt.clientY ? evt.clientY + (document.documentElement.scrollTop || document.body.scrollTop) : evt.pageY;
		} 
	
function sX() {
	return window.pageXOffset ? window.pageXOffset : document.documentElement.scrollLeft ? document.documentElement.scrollLeft : document.body.scrollLeft;
	} 
function sY() {
	return window.pageYOffset ? window.pageYOffset : document.documentElement.scrollTop ? document.documentElement.scrollTop : document.body.scrollTop;
	}
function popUp(evt,oi) {
	if (document.getElementById)
	{
		var wp = pw(); 
		dm = document.getElementById(oi);
		var xs = sX();
		var ys = sY();
		var oh = obH(oi); 
		ds = dm.style; 
		st = ds.visibility; 
		ew = dm.offsetWidth || dm.clip.width || 0;
		if (st == "visible" || st == "show") { 
			ds.visibility = "hidden"; 
			}
		else {
				tv = mY(evt) + 20;  //popup cach link 20px;
				lv = mX(evt) - (ew/4); // lay chieu rong cua man hinh tru chieu rong cua popup/4
				if (lv < (xs + 2)) 
					lv = xs + 2; 
				else if (lv + ew > wp + xs)
					lv = wp + xs - ew - 20;
				if (tv + oh + 30 > ph()+ys)
				tv = tv - oh - 20; 
				lv += 'px';
				tv += 'px';
				ds.left = lv; 
				ds.top = tv; 
				ds.visibility = "visible";
				}
		}
	}


function navPage(){
    var catId = document.database.select.value;
    window.location = 'index.jsp?catId='+catId;
}