function selectAllCheckboxes(checkbox, tableId) {
    var form = checkbox.form; 
    var elements = form.getElements();
    for (i = 0; i <= elements.length; i++) {
        element = elements[i];
        if (element.type == 'checkbox' && element.name.indexOf(tableId) != -1) {
            element.checked = checkbox.checked;
        }
    }
}