function launchWindow(id) {

    //Get the screen height and width
    var maskHeight = $(document).height();
    var maskWidth = $(window).width();

    //Set heigth and width to mask to fill up the whole screen
    $('#mask').css({ 'width': maskWidth, 'height': maskHeight });

    //transition effect		
    $('#mask').fadeIn("fast");
    $('#mask').fadeTo("fast", 0.8);

    //Get the window height and width
    var winH = $(window).height();
    var winW = $(window).width();

    //Set the popup window to center
    $(id).css('top', winH / 2 - $(id).height());
    $(id).css('left', winW / 2 - $(id).width() / 2);

    //transition effect
    $(id).fadeIn(3000);


}

$(document).ready(function () {
    $('.window .close').click(function () {
        $('#mask').hide();
        $('.window').hide();
    });

    $('#mask').click(function () {
        $(this).hide();
        $('.window').hide();
    });
});