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;
    });

}

window.onload = function () {
    connect('btn-upcoming-releases', 'onclick', update_features_block);
    connect('btn-all-time-favourites', 'onclick', update_features_block);
    connect('btn-latest-audio-books', 'onclick', update_features_block);
}