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

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

function changeImages() {
    changeImagesArray(changeImages.arguments);
}

function toggleImages() {
    for (var i = 0; i < toggleImages.arguments.length; i += 2) {
        if (selected == toggleImages.arguments[i]) changeImagesArray(toggleImages.arguments[i + 1]);
    }
}

var selected = '';
var preloadFlag = false;
function preloadImages() {
    if (document.images) {
        newsletter_over = newImage("images/download-newsletter-over.jpg");
        events_over = newImage("images/View-events-over-over.jpg");
      preloadFlag = true;
    }
}