var _closeHandler;
function setupPopup(closeHandler) {
    _closeHandler = closeHandler;
    $('.window .close, #mask').click(function (e) {
        e.preventDefault();
        closeWindow();
    });
}

function fadeInWindow(id) {
    var maskHeight = $(document).height();
    var maskWidth = $(window).width();
    $('#mask').css({ 'width': maskWidth, 'height': maskHeight });

    $('#mask').fadeTo("slow", 0.3);

    positionWindow(id);

    $(id).fadeIn(300);
}

function positionWindow(id) {
    var winH = $(window).height();
    var winW = $(window).width();

    $(id).css('top', winH / 2 - $(id).height() / 2);
    $(id).css('left', winW / 2 - $(id).width() / 2);
}

function closeWindow() {
    $('#mask, .window').hide();
    if (_closeHandler) {
        _closeHandler();
    }
}