Demonstrates how to add sub-menu pages from a separate plugin.

admin-page-framework-add-a-main-menu.php

<?php
/** 
 *  Plugin Name:    Admin Page Framework Demo - Add a Main Menu
 *  Plugin URI:     http://en.michaeluno.jp/admin-page-framework
 *  Description:    Adds a main menu and a sub-menu page.
 *  Author:         Michael Uno
 *  Author URI:     http://michaeluno.jp
 *  Version:        1.0.0
 * 
 */

include( dirname( dirname( __FILE__ ) ) . '/admin-page-framework/library/apf/admin-page-framework.php' );
if ( ! class_exists( 'AdminPageFramework' ) ) {
    return;
}

class APFDemo_MainMenu extends AdminPageFramework {
    
    public function setUp() {
        
        $this->setRootMenuPage( 'Main Menu' );

        $this->addSubMenuItems(
            array(
                'title'         => __( 'Main Page', 'admin-page-framework-test' ),
                'page_slug'     => 'test_main_page',
            )               
        );

        $this->setPageHeadingTabsVisibility( false );        
        
    }
    
    public function do_test_main_page() {
        
        echo "<h3>Main Page</h3>"
            . "<p>This is a main page.</p>";
        
    }
    
}
new APFDemo_MainMenu;

admin-page-framework-add-submenu-pages.php

<?php
/** 
 *  Plugin Name:    Admin Page Framework Demo - Add Sub-menu Pages
 *  Plugin URI:     http://en.michaeluno.jp/admin-page-framework
 *  Description:    Adds a sub-menu page
 *  Author:         Michael Uno
 *  Author URI:     http://michaeluno.jp
 *  Version:        1.0.0
 * 
 */

include( dirname( dirname( __FILE__ ) ) . '/admin-page-framework/library/apf/admin-page-framework.php' );
if ( ! class_exists( 'AdminPageFramework' ) ) {
    return;
}

class APFDemo_AddSubMenuPage extends AdminPageFramework {
    
    public function setUp() {
        
        $this->setRootMenuPageBySlug( 'APFDemo_MainMenu' );
        
        $this->addSubMenuItems(
            array(
                'title'         => __( 'Sub-menu Page', 'admin-page-framework-demo' ),
                'page_slug'     => 'test_add_submenu_page',
            )               
        );        
        
    }
    
    public function do_test_add_submenu_page() {
        
        echo "<h3>Sub-menu Page</h3>"
            . "<p>This is a sub-menu page.</p>";        
        
    }
    
}
new APFDemo_AddSubMenuPage;


class APFDemo_AddPageBySetUpFilter {

    public function __construct() {
        
        // set_up_{class name}
        add_action( 'set_up_APFDemo_MainMenu', array( $this, 'setUp' ) );
        
        // do_{page slug}
        add_action( 'do_test_page_x', array( $this, 'doPage' ) );
        
    }
    
    public function setUp( $oFactory ) {
        $oFactory->addSubMenuItems(
            array(
                'title'         => __( 'Page X', 'admin-page-framework-demo' ),
                'page_slug'     => 'test_page_x',
            )               
        );
    }
    
    public function doPage( $oFactory ) {
        echo "<h3>Page X</h3>"
            . "<p>Show some page contents here.</p>";
    }
    
}
new APFDemo_AddPageBySetUpFilter;