Definition
user_admin_account_validate($form_id, $form_values)
user/user.module, line 2150
Code
<?php
function user_admin_account_validate($form_id, $form_values) {
$form_values['accounts'] = array_filter($form_values['accounts']);
if (count($form_values['accounts']) == 0) {
form_set_error('', t('No users selected.'));
}
}
?>