How to use hook_quicktabs_default_quicktabs

answer: In fact, there is a hook_ctools_plugin_api, so you can put the hook_quicktabs_default_quicktabs implementation into mymodule.quicktabs.inc if you implement the hook_ctools_plugin_api.

example:
mymodule.module

/**
 * Implements hook_ctools_plugin_api().
 */
function mymodule_ctools_plugin_api($module, $api) {
  if ($module == 'quicktabs' && $api == 'quicktabs') {
    return array(
      'version' => '1',
      'path' => drupal_get_path('module', 'mymodule') . '/exports'
    );
  }
}

exports/mymodule.quicktabs.inc

/**
 * Implements hook_quicktabs_default_quicktabs().
 */
function mymodule_quicktabs_default_quicktabs() {
  $items = array();
  ...// the exported quicktabs
  return $items;
}

I think the api should be called "quicktabs_default" then the file name would be mymodule.quicktabs_default.inc (as expected)..
new issue..