function fade(el,start,end) {
	setOpacity(el,start);
	if ((start > end)||(start < end)) {
		setTimeout(function(){fade(el,start+(start > end ? -1 : 1),end)},1);
	}
}

function setOpacity(el,value) {
	el.style.opacity = value/100;
	el.style.filter = 'alpha(opacity=' + value + ')';
}

function isArea(el,e) {
	return !(el.contains ? el.contains(e.toElement) : (el.compareDocumentPosition(e.relatedTarget) & 16));
}

var layer;
function previewReference(el, img, title) {
	// hover efekt
	el.getElementsByTagName('span')[0].style.backgroundPosition = '0 bottom';
	
	// odkryjeme nazev a datum reference
	var referTitle = el.getElementsByTagName('p')[0];
	var referDate = el.getElementsByTagName('p')[1];
	var referUrl = el.getElementsByTagName('p')[2];
	referTitle.style.display = 'block';
	referDate.style.display = 'block';
	referUrl.style.display = 'block';
	
	// vlozime overlay vrstvu
	if (!document.getElementById('overlayLayer')) {
		layer = document.createElement('a');
		layer.id = 'overlayLayer';
		layer.href = img; // cesta k obr. reference (v plnem rozliseni)
		layer.setAttribute('rel', 'lightbox');
		//layer.setAttribute('class', 'thickbox');
		layer.setAttribute('title', title);
		layer.onmouseover = function() {setOpacity(layer,20)}
		layer.onmouseout = function() {setOpacity(layer,0)}
		el.appendChild(layer);
		//fade(layer,0,20);
		setOpacity(layer,0);
		// reinicializace thickboxu
		//tb_reinit('a.thickbox, area.thickbox, input.thickbox');
	}
	
	// odjeti mysi
	el.onmouseout = function(e) {
		e = e || event;
		if (isArea(el,e)) {
			referTitle.style.display = 'none';
			referDate.style.display = 'none';
			referUrl.style.display = 'none';
			el.getElementsByTagName('span')[0].style.backgroundPosition = '0 0';
			el.removeChild(layer);
		}
	}
}

function flipBg(el) {
	var div = el.getElementsByTagName('div');
	for (i = 0; i < div.length; i++) {
		div[i].style.backgroundPosition = '0 bottom';
	}
	el.onmouseout = function() {
		for (i = 0; i < div.length; i++) {
			div[i].style.backgroundPosition = '0 top';
		}
	}
}