Add a type selector to the value form
Overrides Numeric::valueForm
protected function valueForm(&$form, &$form_state) {
if (empty($form_state['exposed'])) {
$form['value']['type'] = array(
'#type' => 'radios',
'#title' => t('Value type'),
'#options' => array(
'date' => t('A date in any machine readable format. CCYY-MM-DD HH:MM:SS is preferred.'),
'offset' => t('An offset from the current time such as "!example1" or "!example2"', array(
'!example1' => '+1 day',
'!example2' => '-2 hours -30 minutes',
)),
),
'#default_value' => !empty($this->value['type']) ? $this->value['type'] : 'date',
);
}
parent::valueForm($form, $form_state);
}