Restrict block visibilty based on menu I want to display a block only on a particular menu-link. 

For example I have a main menu link name: about us and the link: /about

If I restrict the block based on pages and give link as /about , In future the client may change the menu link as /about-us. 

So instead of restricting it based on pages, is there any other module which restrict block visibility based on menu's or How can I custom code it?
if (arg(0) == 'node' &amp;&amp; is_numeric(arg(1))) {
  $active_trail = menu_get_active_trail();
  end($active_trail);
  $nid = 1; // change to nid of parent node you want to check
  if ($active_trail[1] &amp;&amp; $active_trail[1]['link_path'] == 'node/'.$nid) {
    return true;
  } else {
    return false;
  }
}  


You can use the above code to achieve it in Drupal 7.