Embed WordPress Admin in an iframe

By default WordPress doesn’t allow to embed the admin pages into a frame. From wp-includes/default-filters.php:

add_action( 'admin_init', 'send_frame_options_header', 10, 0 );

To enable embedding, remove the action in a plugin:

remove_action( 'admin_init', 'send_frame_options_header' );

Be aware of the security implications. I wouldn’t do that.