function newImage(arg) {
    if (document.images) {
        rslt = new Image();
        rslt.src = arg;
        return rslt;
    }
}

function changeImages() {
    if (document.images && (preloadFlag == true)) {
        for (var i=0; i<changeImages.arguments.length; i+=2) {
            document[changeImages.arguments[i]].src = changeImages.arguments[i+1];
        }
    }
}

var preloadFlag = false;
function preloadImages() {
    if (document.images) {
        nav_contexts_over = newImage("images/shared/nav-contexts-over.gif");
        nav_contexts_over_bio = newImage("images/shared/nav-contexts-over-bio.gif");
        nav_bio_over = newImage("images/shared/nav-bio-over.gif");
        nav_bio_over_career = newImage("images/shared/nav-bio-over-career.gif");
        nav_career_over_bio = newImage("images/shared/nav-career-over-bio.gif");
        nav_career_over = newImage("images/shared/nav-career-over.gif");
        nav_commentary_over_career = newImage("images/shared/nav-commentary-over-career.gif");
        nav_commentary_over = newImage("images/shared/nav-commentary-over.gif");
        nav_loa_over = newImage("images/shared/nav-loa-over.gif");
        nav_loa_over_commentary = newImage("images/shared/nav-loa-over-commentary.gif");
        preloadFlag = true;
    }
}