Why is the Page Title missing on Pages added with add_submenu_page?

Question

Adding sub menus is easy with add_submenu_page and is working fine as long if you define a $parent_slug:

add_submenu_page( $parent_slug, $page_title, $menu_title, $capability, $menu_slug, $function );

if you set the $parent_slug to NULL as described here to hide it from any menu item the title of the page will get ignored ($page_title)

add_submenu_page( NULL, $page_title, $menu_title, $capability, $menu_slug, $function );

I've tested it with all versions from 3.3 up to the latest 4.0

Answer 1

It is a valid question and an issue I have encountered as well.

I did not go through the WP core code to see why the title is missing, but I can offer a solution using the admin_title filter, for people facing a similar problem:

function fix_your_page_title( $admin_title, $title ) {
    if ( get_current_screen()->id === 'your_page_id' && $title === '' ) {
        $admin_title = 'Your page title' . $admin_title;
    }    

    return $admin_title;
}

add_filter( 'admin_title', 'fix_your_page_title', 10, 2 );