Mine

function eventfinder_tax_control($val = '', $max = NULL) {  $items = eventfinder_tax_data();  $form = array(    '#type' => 'select',    '#title' => 'Search by Event Category',    '#default_value' => $val,    '#options' => $items,    '#description' => t('Select event terms to filter by'),    '#extra' => ($max ? ' size=' . $max . ' ' : ''),    '#multiple' => $max,  );  return $form;}