How to filter customize_loaded_components from a theme?

Question

I have written a WordPress theme which uses the customizer a lot. I would like to de-register the widgets panel (I have my reasons). Currently, I'm doing this:

/**
 * Our class for altering the WP theme customizer.
 */
class LXB_AF_Customize {

    public function __construct() {

        [...]

        add_action( 'customize_register', array( $this, 'remove_items' ), 980 );

        [...]

    }

    [...]

    // We're gonna output widgets elsewhere, so we don't need the core widgets panel.
    function remove_items( $wp_customize ) {

        [...] 

        @$wp_customize -> remove_panel( 'widgets' );

    }

}

Which is instantiated in the global scope via:

/**
 * Setup the Theme Customizer settings and controls.
 */
function lxb_af_customizer_init() {
    new LXB_AF_Customize();
}
add_action( 'init' , 'lxb_af_customizer_init' );

This triggers a doing_it_wrong error from core, here: https://github.com/WordPress/WordPress/blob/master/wp-includes/class-wp-customize-manager.php#L1212

That message suggests that I instead use customize_loaded_components:

https://developer.wordpress.org/reference/hooks/customize_loaded_components/

However, as noted on that docs page, customize_loaded_components does not seem to work when invoked from a theme. I can only get it to work from a plugin. In my situation, I don't want to require any particular plugin to be active, in order to use my theme.

Any suggestions?

Answer 1

Since WordPress 4.5, there is a new warning regarding the use of remove_panel with core components (at the moment 'nav_menus' and 'widgets').

The warning states:

Removing WP_Customize_Manager::remove_panel manually will cause PHP warnings. Use the customize_loaded_components filter instead.

Apparently it was added because of some php and javascript errors that seemed to be occurring in WordPress releases from 4.0 to 4.5, when plugins and/or themes were giving contradictory orders, like one trying to modify the widgets panel after another had removed it before.

The warning suggestion, however, is not valid for themes, since customize_loaded_components is fired before them. So this hook called from a theme just won't have place in the right moment of the processing queue and will have no effect.

For 'nav_menus' there is this workaround, which doesn't seem to work for widgets:

$wp_customize->get_panel( 'nav_menus' )->active_callback = '__return_false';

There might be a method to remove the widgets panel effectively without the warning getting printed. But for a general, public usage, it just seems to be against the best practices to remove any of those core components from within a theme.