function swap(id, newSrc) {
    var theImage = findImage(document, id, 0);
    if (theImage) {
        theImage.src = newSrc;
    }

}
function findImage(doc, name, j) {
    var theImage = false;
    if (doc.images) {
        theImage = doc.images[name];
    }

    if (theImage) return theImage;

    if (doc.layers) {
        for (j = 0; j < doc.layers.length; j++) {
            theImage = findImage(doc.layers[j].document, name, 0);
            if (theImage) return theImage;
        }
    }
    return false;
}