Up to release 2018 Greebo: This event is signaled by show() in inc/html.php when an edit form is shown, handlers can use it to provide own edit forms for special content. The whole form can be changed in HTML_EDITFORM_OUTPUT.
Since release 2020 Hogfather: This event is signaled by Editor::show() in inc/Ui/Editor.php when an edit form is shown, handlers can use it to provide own edit forms for special content. The whole form can be changed in HTML_EDITFORM_OUTPUT.
dokuwiki\Form\Form
object for the edit form. See refactor2021 for fallback code for the Form update.