open in new window for external links

I needed the requirement for external links to open up in a new window.
Not sure how you go about coding patches etc so here's the code that does this:

theme_imagemenu_item()

Change this:

if (!empty($item['path'])) {
    $output = '<li class="'. $li_class .'"'. $listyle .'><a href="'. url($item['path']) .'" class="'. $a_class .'"><img src="'.
    base_path() . $item['imagepath'] .'" alt="'. check_plain($item['alt']) .'" title="'. check_plain($item['title'])
    .'" name="imagemenu_'. $prefix .'_'. $item['mid'] .'"'. $script .' /></a>'. $menu .'</li>';
  }

To this:

if (!empty($item['path'])) {
    // adding option so that all external links open in a new window
    $externalLink = '';
    if(strpos(strtolower($item['path']), 'http') !== false) {
        $externalLink = ' target="_blank" ';
    }
    $output = '<li class="'. $li_class .'"'. $listyle .'><a href="'. url($item['path']) .'" class="'. $a_class .'"'.$externalLink.'><img src="'.
    base_path() . $item['imagepath'] .'" alt="'. check_plain($item['alt']) .'" title="'. check_plain($item['title'])
    .'" name="imagemenu_'. $prefix .'_'. $item['mid'] .'"'. $script .' /></a>'. $menu .'</li>';
  }