new toolkit

<?php

function poetic_toolkit_admin_settings() {

    $viewport_setting_description = "Enable this to force the viewport to enable viewport 'width=device-width' and set the scale to 1.0. <strong>This MUST be enabled for other settings in this module to function.</strong>";

    $webapp_setting_description = "Enable this to allow for mobile devices to save the page as a bookmark and load into a webapp wrapper (for iOS and Android).";


    $form['poetic_toolkit_mobile_viewport_setting'] = array(
        '#type' => 'checkbox',
        '#title' => t('Enable Mobile Viewport'),
        '#description' => t($viewport_setting_description),
        '#default_value' => variable_get('poetic_toolkit_mobile_viewport_setting', TRUE),
    );

    $form['poetic_toolkit_enable_webapp_setting'] = array(
        '#type' => 'checkbox',
        '#title' => t('Enable Mobile Web App'),
        '#description' => t($webapp_setting_description),
        '#default_value' => variable_get('poetic_toolkit_enable_webapp_setting', FALSE),
        '#states' => array('visible' => array(':input[name="poetic_toolkit_mobile_viewport_setting"]' => array('checked' => TRUE),),),
    );

  array_unshift($form['#submit'], 'poetic_toolkit_admin_submit');

    return system_settings_form($form);
}

function poetic_toolkit_admin_submit($form, &$form_state) {
  // check if field A is checked
  if(!$form_state['values']['poetic_toolkit_mobile_viewport_setting']) {
    // if it is not then set field B value to 0
    $form_state['values']['poetic_toolkit_enable_webapp_setting'] = 0;

  }
}