function FadeIn(id1, id2) {

    document.getElementById(id1).style.display = 'block';
    opacity(id1, 0, 50, 1000);
    changeOpac(0, id2);
    showElement(id2);
    opacity(id2, 0, 100, 500);
}

function showElement(id1) {
    document.getElementById(id1).style.display = 'block';
}

function FadeOut(id1, id2) {
    document.getElementById(id2).style.display = 'none';
    opacity(id1, 50, 0, 1000);
    document.getElementById(id1).style.display = 'none';
}
function opacity(id, opacStart, opacEnd, millisec) {
    //speed for each frame 
    var speed = Math.round(millisec / 85);
    var timer = 0;

    //determine the direction for the blending, if start and end are the same nothing happens 
    if (opacStart > opacEnd) {
        for (i = opacStart; i >= opacEnd; i--) {
            setTimeout("changeOpac(" + i + ",'" + id + "')", (timer * speed));
            timer++;
        }
    } else
        if (opacStart < opacEnd) {
            for (i = opacStart; i <= opacEnd; i++) {

                setTimeout("changeOpac(" + i + ",'" + id + "')", (timer * speed));
                timer++;

            }
        }
}
//change the opacity for different browsers 
function changeOpac(opacity, id) {
    var object = document.getElementById(id).style;
    object.opacity = (opacity / 100);
    object.MozOpacity = (opacity / 100);
    object.KhtmlOpacity = (opacity / 100);
    object.filter = "alpha(opacity=" + opacity + ")";
}