function flash_element(element) {
    var elmt = document.getElementById(element);

    if (elmt.className == 'flashing_on') {
	elmt.className = 'flashing_off';
    }
    else {
	elmt.className = 'flashing_on';
    }

    return;
}


function begin_flashing(element) {
    window.setInterval("flash_element('" + element + "')", 1000);
}