Adds default theme supports for block themes when the ‘setup_theme’ action fires.

Default custom background callback.

Registers the internal custom header and background routines.

Adds CSS to hide header text for custom logo, based on Customizer setting.

Checks an attachment being deleted to see if it’s a header or background image.

Gets random header image data from registered images in theme.

Do not use. Removes theme support internally without knowledge of those not used by themes directly.

Filters changeset post data upon insert to ensure post_name is intact.

Includes and instantiates the WP_Customize_Manager class.

Adds settings for the customize-loader script.