Settings API updated messages won’t show if custom admin page not hooked into add_options_page()

Been playing around with the Settings API and found that messages (for success or errors) are only displayed when a settings page is hooked into WordPress menu via add_options_page(). Anything else will not work e.g. add_dashboard_page(). Would like to know if this is true? Sample code I tried with is the answer containing the “RegisteredSettingsTest” class at Where to hook register_settings for Settings API when also want to update options outside of Settings API?

Thanks Chip (excellent Settings API tutorial) and t31os (great snippet of code for quick testing) for both your suggestions.

I did some further digging and found that the default messages can indeed be displayed if I hook into any menu but only if the function settings_errors() is called.

For example, modifying t31os code as follows:

<div class="wrap">
  <h2>Test</h2>
  <?php settings_errors(); ?>
  <form action="options.php" method="post">

Custom error messages can also be added by calling the add_settings_error() function for displaying success or failure message by specifying the $type parameter as either ‘error’ or ‘updated’.