Feature: #96899 - New PSR-14 event: ModifyGenericBackendMessagesEvent

Description

A new PSR-14 event \TYPO3\CMS\Backend\Controller\Event\ModifyGenericBackendMessagesEvent has been introduced. It serves as direct replacement for the now removed hook $GLOBALS['TYPO3_CONF_VARS']['SC_OPTIONS']['t3lib/class.t3lib_befunc.php']['displayWarningMessages'] .

Example

Registration of an event listener in your extension's Services.yaml:

MyVendor\MyPackage\Backend\MyEventListener:
  tags:
    - name: event.listener
      identifier: 'my-package/backend/add-message'

The corresponding event listener class:

use TYPO3\CMS\Backend\Controller\Event\ModifyGenericBackendMessagesEvent;
use TYPO3\CMS\Core\Messaging\FlashMessage;

class MyEventListener {

    public function __invoke(ModifyGenericBackendMessagesEvent $event): void
    {
        // Add a custom message
        $event->addMessage(new FlashMessage('My custom message'));
    }
}

Impact

The PSR-14 event allows to add or alter messages that are displayed in the "About" module (default start module of the TYPO3 Backend).

Extensions such as "Reports" already use this event to display custom messages based on the status of the system.