if (document.images) {
    bar_homeOff = new Image();
    bar_homeOff.src = "En_Img/bar_home_off.jpg";
    bar_homeOn = new Image();
    bar_homeOn.src = "En_Img/bar_home_on.jpg";

    bar_aboutOff = new Image();
    bar_aboutOff.src = "En_Img/bar_about_off.jpg";
    bar_aboutOn = new Image();
    bar_aboutOn.src = "En_Img/bar_about_on.jpg";

    bar_activOff = new Image();
    bar_activOff.src = "En_Img/bar_activ_off.jpg";
    bar_activOn = new Image();
    bar_activOn.src = "En_Img/bar_activ_on.jpg";

    bar_calendarOff = new Image();
    bar_calendarOff.src = "En_Img/bar_calendar_off.jpg";
    bar_calendarOn = new Image();
    bar_calendarOn.src = "En_Img/bar_calendar_on.jpg";

    bar_involvedOff = new Image();
    bar_involvedOff.src = "En_Img/bar_involved_off.jpg";
    bar_involvedOn = new Image();
    bar_involvedOn.src = "En_Img/bar_involved_on.jpg";

    bar_teachOff = new Image();
    bar_teachOff.src = "En_Img/bar_teach_off.jpg";
    bar_teachOn = new Image();
    bar_teachOn.src = "En_Img/bar_teach_on.jpg";

    bar_contactOff = new Image();
    bar_contactOff.src = "En_Img/bar_contact_off.jpg";
    bar_contactOn = new Image();
    bar_contactOn.src = "En_Img/bar_contact_on.jpg";
}

function buttondown(buttonname) {
    if (document.images) {
        document[buttonname].src = eval(buttonname + "On.src");
    }
}

function buttonup(buttonname) {
    if (document.images) {
        document[buttonname].src = eval(buttonname + "Off.src");
    }
}