A fully-featured web app in 30-lines with Agile UI.

ui-app.php

<?php
$app = new \atk4\ui\App('Hello World');
$db = new \atk4\data\Persistence_SQL($dsn);

$app->initLayout('Fluid');

$app->menu->addItem(['Demo1', 'icon'=>'form'], ['demo'=>'form']);
$app->menu->addItem(['Demo2', 'icon'=>'crud'], ['demo'=>'crud']);

$this->layout->add('View', ['view box'])->set('Entire Web APP in 30 lines of code!');

$demo = $app->stickyGET('demo');
if ($demo == 'form') {
    $form = $this->layout->add('Form');
    $form->setModel(new User($db), ['name', 'email']);
    $form->onSubmit(function($form){
        $form->model->save();
        return 'Created successfully';
    });
} elseif ($demo == 'crud') {
    $crud = $this->layout->add('CRUD');
    $crud->setModel(new User($db));
}

echo $app->render();

class User extends \atk4\data\Model {
    function init() {
        parent::init();
        $this->addField('name');
        $this->addField('email', ['type'=>'email']);
        $this->addField('created', ['type'=>'datetime', 'default'=>new DateTime()]);
    }
}