suffix post title with post ID

// suffix it everywhere

add_filter( 'the_title', 'gowp_post_id_title_suffix' ); // registers our action filter; the 2nd parameter is the name of the function we'll use to return the (possibly) updated title
function gowp_post_id_title_suffix( $title ) {
	global $post; // get the current post object
	if ( 'post' == $post->post_type ) { // only apply our change to Posts
		$title .= " - {$post->ID}"; // append the post ID to the title
	}
	return $title; // return the title, even if we haven't modified it
}

// don't suffix  it to menus AND sidebar
add_filter( 'the_title', 'gowp_post_id_title_suffix' ); // registers our action filter; the 2nd parameter is the name of the function we'll use to return the (possibly) updated title
function gowp_post_id_title_suffix( $title ) {
	global $post; // get the current post object
	if ( ( 'post' == $post->post_type ) && in_the_loop() ) { // only apply our change to Posts while in the loop
		$title .= " - {$post->ID}"; // append the post ID to the title
	}
	return $title; // return the title, even if we haven't modified it
}

// don't suffix to menu only
add_action( 'loop_start', 'gowp_pttf_add' );
add_action( 'loop_end', 'gowp_pttf_remove' );

add_action( 'dynamic_sidebar_before', 'gowp_pttf_add' );
add_action( 'dynamic_sidebar_after', 'gowp_pttf_remove' );

function gowp_pttf_add() {
	add_filter( 'the_title', 'gowp_pttf_do' );
}
function gowp_pttf_remove() {
	remove_filter( 'the_title', 'gowp_pttf_do' );
}
function gowp_pttf_do( $title ) {
	global $post; // get the current post object
	if ( $post && ( 'post' == $post->post_type ) ) { // only apply our change to Posts
		$title .= " - {$post->ID}"; // append the post ID to the title
	}
	return $title; // return the title, even if we haven't modified it
}