Display a single views grouping.
function theme_views_view_grouping($vars) {
$view = $vars['view'];
$title = $vars['title'];
$content = $vars['content'];
$output = '<div class="view-grouping">';
$output .= '<div class="view-grouping-header">' . $title . '</div>';
$output .= '<div class="view-grouping-content">' . $content . '</div>';
$output .= '</div>';
return $output;
}