New Twiddle

controllers.application.js

import Ember from 'ember';

export default Ember.Controller.extend({
  appName: 'Ember Twiddle',
  menuOpened: true,
  showModal: false
});

templates.application.hbs

Show modal: {{showModal}}<br />
Menu opened: {{menuOpened}}

<br><br>
{{#if showModal}}
Modal:
<button {{action (mut menuOpened) true on="click"}} {{action (mut showModal) false on="click"}}>
Close modal
</button>
{{else}}

{{/if}}

{{#if menuOpened}}
Menu:
<button {{action (mut showModal) true on="click"}} {{action (mut menuOpened) false on="click"}}>
Show modal
</button>

{{/if}}
<br>
<br>

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"
  }
}