function unselect(button) {
    if (button.id.substr(0,3)=='btn') {
    	removeElementClass(button,'selected');
    }
}

function update_features_block(caller) {
    forEach(getElementsByTagAndClassName('a', 'selected'), unselect);
    addElementClass(this, 'selected');
    $('load').innerHTML='<div class="home-page-books p"><ul><li>Loading...</li></ul></div>';
    var d = doXHR('/block/'+this.id+'/');
    d.addCallback(function (req) {
    	$('load').innerHTML = req.responseText;
    });

}

function show_ad() {
    var d = loadJSONDoc('/advertises/show/');
    d.addCallback(function (req) {
	for (i in req.slots) {
	    if (req[req.slots[i]] == undefined ) {
		hideElement($(req.slots[i]).parentNode.parentNode);
	    } else {
		showElement($(req.slots[i]).parentNode.parentNode);
		$(req.slots[i]).src = req[req.slots[i]].img;
		$(req.slots[i]).parentNode.href = req[req.slots[i]].url;
	    }
	}
    });
    setTimeout("show_ad()",20*1000);
}

window.onload = function () {
//    show_ad()
}