How to have “the most used tags” taxonomy always expanded?

How can I have some taxonomies to always have “the most used tags” displayed when a new post is being created.

Thanks.

There does not appear to be any way to hook into that from inside PHP

http://core.trac.wordpress.org/browser/tags/3.3.1/wp-admin/includes/meta-boxes.php#L300

So JavaScript will probably best suit as a quick and easy solution.

add_action( 'admin_footer-post-new.php', 'wpse_45149_inject_script' );
function wpse_45149_inject_script() {

    $expand_for = array( 'post_tag' ); // add taxonomy names here

    // build a nice jQuery query
    foreach ( $expand_for as &$tax_name ) $tax_name="#link-".$tax_name;
    $expand_for = implode( ',', $expand_for );

    ?>
        <script type="text/javascript">
            jQuery(document).ready(function() {
                jQuery('<?php echo $expand_for; ?>').click();
            })
        </script>
    <?php

}

You should probably wp_enqueue_script this script instead (always set position to “footer”). And also hook to the edit.php pages if necessary. Moreover, $expanded_for should probably be escaped.