function openPopup(url, name, width, height) {
    width += 32;
    height += 96;
    
    var left = (screen.width - width) / 2;
    var top = (screen.height - height) / 2;
    
    var popup = window.open(url, name, "width=" + width + ", height=" + height +
        ", left=" + left + ", top=" + top + ", location=no, menubar=no, status=no" +
        ", toolbar=no, scrollbars=yes, resizable=no");
        
    popup.focus();
}

function tabActive(id){
    document.getElementById(id).className = 'active';
    document.getElementById(id + '_left').src = '/ass_pages/images/navigation/active_left.png';
    document.getElementById(id + '_right').src = '/ass_pages/images/navigation/active_right.png';
}

function tabInactive(id, className) {
    document.getElementById(id).className = className;
    document.getElementById(id + '_left').src = '/ass_pages/images/navigation/' + className + '_left.png';
    document.getElementById(id + '_right').src = '/ass_pages/images/navigation/' + className + '_right.png';
}