Custom Post Types are hidden by default in the nav-menu page and there's no clean way to prevent that

[louisremi]

The function wp_initial_nav_menu_meta_boxes marks all non-built-in meta-boxes as hidden.

This has some unexpected consequences: register_post_type has an option show_in_nav_menus and one would guess that setting this to true would display a meta-box for this post type on the nav-menu UI, but it doesn't.

The real problem is that there is no clean way to prevent that behavior: the only hook available is hidden_meta_boxes and using it to un-hide meta-boxes also overrides screen-options actually selected by the user. (default_hidden_meta_boxes is never executed for nav-menus, because of wp_initial_nav_menu_meta_boxes).

I'm not sure why wp_initial_nav_menu_meta_boxes was written in the first place, but it should at least provide a hook to add additional $initial_meta_boxes.

[louisremi]

Add a 'initial_nav_menu_meta_boxes' filter

[johnbillion]

I don't think your patch is the correct approach. If a custom post type or taxonomy specifies show_in_nav_menus as true then they should show up on the nav menu screen without needing to hook into a filter too.

[louisremi]

@johnbillion I agree with you but I was guessing wp_initial_nav_menu_meta_boxes was here for a reason. The alternative is to drop that function and its single function call in nav-menus.php altogether.

[SergeyBiryukov]

Duplicate of #16828.