New Twiddle

components.my-modal.js

import Ember from 'ember';

export default Ember.Component.extend({
  actions: {
    closeModal() {
      console.log('close the modal');
      this.set('closed', true);
    }
  }
});

controllers.application.js

import Ember from 'ember';

export default Ember.Controller.extend({
  appName: 'Ember Twiddle'
});

templates.application.hbs

<h1>Welcome to {{appName}}</h1>
<br>
<br>
{{outlet}}
<br>
<br>
{{#my-modal as |closeModal|}}
  <h2>Hello from modal</h2>
  <button onClick={{action closeModal}}>Close me</button>
{{/my-modal}}

templates.components.my-modal.hbs

<div style="border: 1px solid black">
{{yield (action 'closeModal')}}
<p>Closed? {{closed}}</p>
</div>

twiddle.json

{
  "version": "0.12.1",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/1.11.3/jquery.js",
    "ember": "2.12.0",
    "ember-template-compiler": "2.12.0",
    "ember-testing": "2.12.0"
  },
  "addons": {
    "ember-data": "2.12.1"
  }
}