New Twiddle

components.my-component.js

import Ember from 'ember';

export default Ember.Component.extend({
  showContent: false,
  didInsertElement(){
    this._super(...arguments);
    Ember.run.next(this, this.displayModalContent);
  },
  displayModalContent(){
    this.set('showContent',true);
  },
  actions:{
    test(){
      this.set('showContent',true);
    }
  }
});

controllers.application.js

import Ember from 'ember';

export default Ember.Controller.extend({
  appName: 'Ember Twiddle',
  displayModal: false,
  actions:{
    toggleModal(){
      this.toggleProperty('displayModal');
    }
  }
});

styles.app.css

body {
  margin: 12px 16px;
  font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif;
  font-size: 12pt;
  background: lightblue;
}
.content{
  background: white;
  height:200px;
  width: 300px;
  transform: scale(0.7);
	opacity: 0;
	transition: all 0.3s;
}
.show{
  transform: scale(1);
	opacity: 1;
}

templates.application.hbs

<button {{action 'toggleModal'}}>Toggle Modal</button>
<br>
<br>
{{#if displayModal}}
{{#my-component}}
<h2>modal content</h2>
{{/my-component}}
{{/if}}
{{outlet}}
<br>
<br>

templates.components.my-component.hbs

<div class="content {{if showContent "show"}}">
 {{yield}}
</div>

twiddle.json

{
  "version": "0.7.2",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/1.11.3/jquery.js",
    "ember": "2.4.4",
    "ember-data": "https://cdnjs.cloudflare.com/ajax/libs/ember-data.js/2.4.3/ember-data.js",
    "ember-template-compiler": "2.4.4"
  }
}