ty very much for you reply.
I have to change my question then.
I’m trying to make a new admin menu voice.
Very much like piklist about/welcome page.

I start by adding in my plugin php:

add_filter('piklist_admin_pages', 'my_custom_admin_pages');
  function my_custom_admin_pages($pages) 
  {
    $pages[] = array(
      'page_title' => __('Page title')
      ,'menu_title' => __('Menu title')
      ,'capability' => 'manage_options'
      ,'menu_slug' => 'mycustomadminpages'
      ,'menu_icon' => MY_PLUGIN_URL.'imgs/my-icon.png'
      ,'page_icon' => MY_PLUGIN_URL.'imgs/my-icon.png'
      ,'single_line' => true
      ,'default_tab' => 'Basic'
    );
  
    return $pages;
  }

that correctly create the ‘Menu title’ menu button (with correct icon)
I miss how to specify that /parts/admin-pages/mycustompage.php will be the target of ‘Menu title’ menu button link.
Currently it displays a blank page with ‘Page title’

Sorry for the silly question but I think that could integrate your documentation page
Documentation: Settings / Admin Page Parameters

yes i know. never understimate the stupidity of some of yours readers.

Steve thankyou very much.
I saw the welcome page and ironically I displayed it in my new admin section.
Now I realize I cannot display MY page because I forgot to add
Plugin Type: Piklist
in my plugin
all other functions worked well. Not the folder structure

Really sorry to have wasted your time
Hopefully this will be of some utility to others

Keep on with your work
Piklist rocks !!!