/**
 * Checks/unchecks all tables
 *
 * @param   string   the form name
 * @param   boolean  whether to check or to uncheck the element
 *
 * @return  boolean  always true
 */
function setCheckboxes(the_form, do_check) {
    var elts = document.forms[the_form].elements['check[]'];
    var elts_cnt = 'undefined' != typeof(elts) ? elts.length : 0;
    if (elts_cnt) {
        for (var i = 0; i < elts_cnt; i++) {
            elts[i].checked = do_check;
        }
    }
}