Add Tab for "Sent Messages"

Hi there,

instead of using the select folder Form on top of the Messages list (e.g. when opening the inbox) I would like to have another tab which says "sent messages" next to the "list" tab.
I managed to get this by creating an alias which maps "privatemsg/list/1" on "privatemsg/sent" and then I edited the privatemsg menu_hook (in privatemsg.module) and added the following entry:

$items[] = array(
'path' => 'privatemsg/sent',
'title' => t('Sent'),
'callback' => 'privatemsg_list',
'callback arguments' => array(NULL),
'access' => !$user->uid || $access,
'type' => MENU_LOCAL_TASK,
'weight' => -9,
);

Now the new Tab is showing up. Unfortunately the tab does not change the color when it's active (in my theme Glossyblue active tabs are white and non-active tabs are grey). The correct list, namely the sent messages, are displayed but the tab remains non-active. Instad the "list" tab remains active (visually).

This is probably because this tab only maps on the original url "privatemsg/list/1" via aliasing and this is under the menu item for the tab "list".

Does anyone know, how to change the color for this tab when clicking it?

Thanks for your support.

best regards,
Hauke