PlugIn ? Not Yet ;-(
Wait for some kind Developer to code this feature ;-) 

i'll see what it will take Private_River working for 1.8 

@Steve The views has changed a little bit in elgg 1.8, for instance, part of the code of the nav.php is in root/pages/river

The part of the code that's there is the one that let you choose which tab is going to be the default one.

If I were to find the correct view where the tabs are being generated I could extend the view. Probably, I don't know lol

@steve :Thnanks Steve your help would be really appriciated

yeah I too browsed through several files of river but was not able to figure out where the view is being generated. :P

I figured out how to do it but it seems the file I need to edit to get it done is engine/lib/river.php and I can seem to override that file.

Haven't really studied the code, but my first guess would be to try and unregister the menu item.

if (elgg_get_context() == 'activity') {

elgg_unregister_menu_item('filter', 'all');

}

I conclude this based on the html code:

<ul class="elgg-menu elgg-menu-filter elgg-menu-hz elgg-menu-filter-default"><!-- developers:begin navigation/menu/elements/item --><li class="elgg-menu-item-all elgg-state-selected"><a href="http://localhost/hypetest18/activity/all" title="" confirm="">All</a></li><!-- developers:end navigation/menu/elements/item --><!-- developers:begin navigation/menu/elements/item --><li class="elgg-menu-item-mine"><a href="http://localhost/hypetest18/activity/owner/ismayil.khayredinov" title="" confirm="">Mine</a></li><!-- developers:end navigation/menu/elements/item --><!-- developers:begin navigation/menu/elements/item --><li class="elgg-menu-item-friend"><a href="http://localhost/hypetest18/activity/friends/ismayil.khayredinov" title="" confirm="">Friends</a></li><!-- developers:end navigation/menu/elements/item --></ul>

ul.elgg-menu-filter

li.elgg-menu-item-all

@Ismayil Khayredinov Great piece of code! I have that same from html code, I will study the code next week I think, I am tied up with a lot of stuffs I need to do hehe

Change root/pages/river.php to this:

<?php
/**
 * Main activity stream list page
 */

$options = array();

$page_type = preg_replace('[\W]', '', get_input('page_type', 'friends'));
$type = preg_replace('[\W]', '', get_input('type', 'friends'));
$active_section =
$subtype = preg_replace('[\W]', '', get_input('subtype', ''));
if ($subtype) {
    $selector = "type=$type&subtype=$subtype";
} else {
    $selector = "type=$type";
}

if ($type != 'friends') {
    $options['type'] = $type;
    if ($subtype) {
        $options['subtype'] = $subtype;
    }
}

switch ($page_type) {
    case 'mine':
        $title = elgg_echo('river:mine');
        $page_filter = 'mine';
        $options['subject_guid'] = elgg_get_logged_in_user_guid();
        break;
    case 'friends':
        $title = elgg_echo('river:friends');
        $page_filter = 'friends';
        $options['relationship_guid'] = elgg_get_logged_in_user_guid();
        $options['relationship'] = 'friend';
        break;
    default:
        $title = elgg_echo('river:friends');
        $page_filter = 'friends';
                $options['relationship_guid'] = elgg_get_logged_in_user_guid();
        $options['relationship'] = 'friend';
        break;
}

$activity = elgg_list_river($options);

$content = elgg_view('core/river/filter', array('selector' => $selector));

$sidebar = elgg_view('core/river/sidebar');

$params = array(
    'content' =>  $content . $activity,
    'sidebar' => $sidebar,
    'filter_context' => $page_filter,
    'class' => 'elgg-river-layout',
);

$body = elgg_view_layout('content', $params);

echo elgg_view_page($title, $body);

@ib Right, like I said, I can do that, it is overriding the core instead of editing the core I am trying to do.

@Ismayil Thanks I will work on that

Ibrahim Hasan Actually that is not going to accomplish our goal here. Overriding core files is not recommended. That is a bad trick, 'cause actually what I want to code is only to show two tabs, not three.

@Steve Keep us updated! Let's do this! haha