// Generate a new Announcement Popup Content WYSIWYG editor field for the announcements function custom_popup_content_field( $fields ) { $fields[] = [ 'name' => 'Announcement Popup Content', 'desc' => 'Enter the popup content for this announcement.', 'id' => 'announcement_popup_content', 'type' => 'wysiwyg', ]; return $fields; } add_filter( 'timeline_express_custom_fields', 'custom_popup_content_field' );