gistfile1.php

// one field limited by sum
new GWLimitBySum(array(
    'form_id' => 113,
    'field_id' => 13.3,
    'limit' => 8,
    'limit_message' => 'Sorry, there are no more tickets!',
    'validation_message' => 'You ordered %1$s tickets. There are only %2$s tickets left.',
    'approved_payments_only' => false,
    'hide_form' => false
    ));

// and now another on the same form
new GWLimitBySum(array(
    'form_id' => 113,
    'field_id' => 16.3,
    'limit' => 25,
    'limit_message' => 'Sorry, there are no more soccer balls!',
    'validation_message' => 'You ordered %1$s tickets. There are only %2$s tickets left.',
    'approved_payments_only' => false,
    'hide_form' => false
    ));