Switching between tabs in WordPress Theme Options in PHP

// Fist you need to specify tabs

function pn_get_settings_page_tabs() {
     $tabs = array(
          'general' => 'General',
          'user_manual' => 'User Manual'
     );
     return $tabs;
}


// Then, you can generate tabs
function pn_admin_options_page_tabs( $current = 'general' ) {
     if ( isset ( $_GET['tab'] ) ) :
          $current = $_GET['tab'];
     else:
          $current = 'general';
     endif;
     $tabs = pn_get_settings_page_tabs();
     $links = array();
     foreach( $tabs as $tab => $name ) :
          if ( $tab == $current ) :
               $links[] = '<a class="nav-tab nav-tab-active" href="?page=settings_page&tab='.$tab.'">'.$name.'</a>';
          else :
               $links[] = '<a class="nav-tab" href="?page=setting_page&tab='.$tab.'">'.$name.'</a>';
          endif;
     endforeach;
     echo '<div id="icon-themes" class="icon32"><br /></div>';
     echo '<h2 class="nav-tab-wrapper">';
     foreach ( $links as $link )
          echo $link;
     echo '</h2>';
}