Show all post tags on post edit screen/sidebox

I am looking for a way to show all post tags on post edit screen/tags sidebox in WordPress admin section. By default WordPress shows 45 most used tags but I need a way to list all tags there or at least increase this limit.

I found similar question here Showing all tags in admin -> edit post. But it suggests to edit/modify WordPress core files which is not what I really want. Because upgrading WordPress will be a huge problem then.

I also could not find anything in Google search. So is there are way to list all or more than 45 tags on post edit page.

Answers:

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Method 1

I’d say the easiest way to do it is use the get_terms_args filter and unset the number limit if the context is right (the AJAX request to get the tag cloud):

function wpse_64058_all_tags ( $args ) {
    if ( defined( 'DOING_AJAX' ) && DOING_AJAX && isset( $_POST['action'] ) && $_POST['action'] === 'get-tagcloud' )
        unset( $args['number'] );
    return $args;
}

add_filter( 'get_terms_args', 'wpse_64058_all_tags' );

Note: In the edit box the link will still read “Choose from the most used tags”, even though we’re now displaying all of them.

Edit: As @bonger suggested, you could determine the post type from the referer:

if ( $qs = parse_url( wp_get_referer(), PHP_URL_QUERY ) ) {
    parse_str( $qs, $args );

    if ( ! empty( $args['post_type'] ) )
        $post_type = $args['post_type'];
    elseif ( ! empty( $args['post'] ) )
        $post_type = get_post_type( $args['post'] );
    else
        $post_type = 'post';
}

Method 2

Addition to TheDeadMedic’s answer, to show ALL tags:

if ( defined( 'DOING_AJAX' ) && DOING_AJAX && isset( $_POST['action'] ) && $_POST['action'] === 'get-tagcloud' ) {
    unset( $args['number'] );
    $args['hide_empty'] = 0;
}
return $args;

Method 3

Just adding some basic relevant info:

When setting a taxonomy setting to 'hierarchical'=>true it will use the category format side box and will show all terms by default.

All methods was sourced from stackoverflow.com or stackexchange.com, is licensed under cc by-sa 2.5, cc by-sa 3.0 and cc by-sa 4.0