Creates in-page tabs with Admin Page Framework v3. This is an example plugin introduced in the tutorial, Create In-page Tabs (http://en.michaeluno.jp/admin-page-framework/tutorials-v3/04-create-inpage-tabs/).

tutorials-04-create-inpage-tabs.php

<?php
/* 
    Plugin Name:    Admin Page Framework Tutorial 04 - Create In-page Tabs
    Plugin URI:     http://en.michaeluno.jp/admin-page-framework
    Description:    Creates in-page tabs with Admin Page Framework v3
    Author:         Michael Uno
    Author URI:     http://michaeluno.jp
    Version:        1.0.1
    Requirements:   PHP 5.2.4 or above, WordPress 3.4 or above. Admin Page Framework 3.0.0 or above
*/

// Include the library file. Set your file path here.
include( dirname( dirname( __FILE__ ) ) . '/admin-page-framework/library/apf/admin-page-framework.php' );

    
// Extend the class
class APF_Tabs extends AdminPageFramework {
    
    // Define the setUp() method to set how many pages, page titles and icons etc.
    public function setUp() {
                   
        // Create the root menu
        $this->setRootMenuPage(
            '4. Tabs',    // specify the name of the page group
            'http://lh4.googleusercontent.com/-z7ydw-aPWGc/UwpeB96m5eI/AAAAAAAABjs/Brz6edaUB58/s800/demo04_16x16.png'   // menu icon
        );   
                           
        // Add the sub menu item
        $this->addSubMenuItems(   
            array(
                'title'         => 'My Tabs',        // page title
                'page_slug'     => 'my_tabs',    // page slug
                'screen_icon'   => 'https://lh3.googleusercontent.com/-Z5OeZOGzN3c/UilDgCX9WjI/AAAAAAAABS4/mf7L8GGJRTc/s800/demo04_01_32x32.png'     // page screen icon for WP 3.7.x or below
            )        
        );  
        
        // Add in-page tabs
        $this->addInPageTabs(
            'my_tabs',    // set the target page slug so that the 'page_slug' key can be omitted from the next continuing in-page tab arrays.
            array(
                'tab_slug'  =>    'my_tab_a',    // avoid hyphen(dash), dots, and white spaces
                'title'     =>    __( 'Tab A', 'admin-page-framework-tutorial' ),
            ),        
            array(
                'tab_slug'  =>    'my_tab_b',
                'title'     =>    __( 'Tab B', 'admin-page-framework-tutorial' ),
            ),                    
            array(
                'tab_slug'  =>    'my_tab_c',
                'title'     =>    __( 'Tab C', 'admin-page-framework-tutorial' ),
            )
        );    

        $this->setPageHeadingTabsVisibility( false );    // disables the page heading tabs by passing false.
        $this->setInPageTabTag( 'h2' );        // sets the tag used for in-page tabs
        
    }
    
    /**
     * One of the predefined callback method.
     * 
     * @remark      content_{page slug}
     */
    public function content_my_tabs( $sContent ) {       
        return $sContent 
            . '<h3>Page Content Filter</h3>'
            . '<p>This is inserted by the the page <em>content_</em> filter, set in the <b><i>\'content_ + page slug\'</i></b> method.</p>';
    }
    
    /**
     * One of the predefined callback method.
     * 
     * @remark      content_{page slug}_{tab slug}
     */    
    public function content_my_tabs_my_tab_b( $sContent ) {      
        return $sContent 
            . '<h3>Tab Content Filter</h3>'
            . '<p>This is the second tab! This is inserted by the <b><i>\'content_ + page slug + _ + tab slug\'</i></b> method.</p>';
            
    }
    
    /**
     * One of the predefined callback method.
     * 
     * @remark      content_{page slug}_{tab slug}
     */        
    function content_my_tabs_my_tab_c( $sContent ) {          
        return $sContent 
            . '<h3>Tab Content Filter</h3>'
            . '<p>This is the third tab!.</p>';
    }    
   
}

// Instantiate the class object.
new APF_Tabs;
    
// That's it!! See, it's very short and easy, huh?

content_ + page slug\ And content_ + page slug + _ + tab slug\ shows error. Any suggestion?

i have same error too...