var popups = new Array();

function openPopup(width, height, title, url) {

    var left = (screen.availWidth / 2) - (width / 2);
    var top = (screen.availHeight / 2) - (height / 2);
    var popup = window.open(url, title, 'left=' + left + ',top=' + top + ',height=' + height + ',width=' + width + ',scrollbars=yes,modal=yes');

    popups.push(popup);
}

function closeAllPopups() {
    for (i = 0; i < popups.length; i++) {
        popups[i].close();
    }
}