add hooks for subgroupnav showing

EVENTS.txt

@@ -100,6 +100,12 @@ StartPublicGroupNav: Showing the public group nav menu
 EndPublicGroupNav: At the end of the public group nav menu
 - $action: the current action
 
+StartSubGroupNav: Showing the subscriptions group nav menu
+- $action: the current action
+
+EndSubGroupNav: At the end of the subscriptions group nav menu
+- $action: the current action
+
 RouterInitialized: After the router instance has been initialized
 - $m: the Net_URL_Mapper that has just been set up
 

lib/subgroupnav.php

@@ -74,6 +74,8 @@ class SubGroupNav extends Widget
 
         $this->out->elementStart('ul', array('class' => 'nav'));
 
+        if (Event::handle('StartSubGroupNav', array($this))) {
+
             $this->out->menuItem(common_local_url('subscriptions',
                                                   array('nickname' =>
                                                         $this->user->nickname)),
@@ -106,6 +108,10 @@ class SubGroupNav extends Widget
                                      $action == 'invite',
                                      'nav_invite');
             }
+
+            Event::handle('EndSubGroupNav', array($this));
+        }
+
         $this->out->elementEnd('ul');
     }
 }