Slack example

controllers.application.js

import Ember from 'ember';

export default Ember.Controller.extend({
});

router.js

import Ember from 'ember';
import config from './config/environment';

const Router = Ember.Router.extend({
  location: 'none',
  rootURL: config.rootURL
});

Router.map(function() {
  this.route('foo');
  this.route('bar');
});

export default Router;

routes.application.js

import Ember from 'ember';

export default Ember.Route.extend({
  actions: {
    didTransition() {
      this.controller.set('isNested', false);
    }
  }
});

routes.bar.js

import Ember from 'ember';

export default Ember.Route.extend({
  actions: {
    didTransition() {
      let appController = Ember.getOwner(this).lookup('controller:application');
      appController.set('isNested', true);
    }
  }
});

routes.foo.js

import Ember from 'ember';

export default Ember.Route.extend({
  actions: {
    didTransition() {
      let appController = Ember.getOwner(this).lookup('controller:application');
      appController.set('isNested', true);
    }
  }
});

templates.application.hbs

{{#if isNested}}
  <h1>My cool header for nested routes</h1>
  <br>
  <br>
{{/if}}
{{outlet}}
<br>
<br>

templates.bar.hbs

My bar route 
<br>
go to {{#link-to "index"}}index{{/link-to}}

templates.foo.hbs

My foo route 
<br>
go to {{#link-to "index"}}index{{/link-to}}

templates.index.hbs

Index route also known as "/"
<br>
go to {{#link-to "foo"}}foo{{/link-to}}
<br>
go to {{#link-to "bar"}}bar{{/link-to}}

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"
  }
}