<fieldset>
  <div class="inline-edit-col">
    <label><span class="title"><?php _e( 'Groups', 'tag-groups' ) ?></span>
      <span class="input-text-wrap">

        <select id="term-group-option" name="term-group" class="ptitle">
          <option value="0" ><?php _e( 'not assigned', 'tag-groups' ) ?></option>
          <?php foreach ( $term_groups as $term_group ) :
            ?>
            <option value="<?php echo $term_group['term_group']; ?>"><?php echo htmlentities( $term_group['label'], ENT_QUOTES, "UTF-8" ); ?></option>
          <?php endforeach; ?>
        </select>

        <?php // id must be "tag-groups-option-nonce" because otherwise identical with "Add New Tag" form on the left side. ?>
        <input type="hidden" name="tag-groups-nonce" id="tag-groups-option-nonce" value="" />
        <input type="hidden" name="tag-groups-taxonomy" id="tag-groups-taxonomy" value="<?php echo $screen->taxonomy; ?>" />
      </span>
    </label>
  </div>
</fieldset>