New Twiddle

components.foo-bar.js

import Ember from 'ember';

export default Ember.Component.extend({
  
  isEditMode: true,
  isTextArea: false,
  
  actions: {
    startEdit() {
      this.toggleProperty('isEditMode');
    }
  }
  
});

controllers.application.js

import Ember from 'ember';

export default Ember.Controller.extend({
  appName: 'Ember Twiddle',
  
  foo: "Foo"
});

templates.application.hbs

<h1>Welcome to {{appName}}</h1>
<br>
<br>
<br>
{{#foo-bar value=value as |toggleAction component|}}
  {{component.value}}
{{else}}
  {{input value=foo focus-out=toggleAction}}
{{/foo-bar}}

templates.components.foo-bar.hbs

{{#if isEditMode}}
  {{#if hasBlock}}
    {{yield (action "startEdit") this}}
  {{else if isTextArea}}
    {{textarea value=value focus-out=(action "editComplete")}}
  {{else}}
    {{input value=value focus-out=(action "editComplete")}}
  {{/if}}
{{else}}
  {{yield (action "startEdit") this}}
  {{#if hasBlock}}
    {{yield}}
  {{else}}
    <div {{action "startEdit"}}> {{value}} </div>
  {{/if}}
{{/if}}

twiddle.json

{
  "version": "0.7.1",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/1.11.3/jquery.js",
    "ember": "https://cdnjs.cloudflare.com/ajax/libs/ember.js/2.4.3/ember.debug.js",
    "ember-data": "https://cdnjs.cloudflare.com/ajax/libs/ember-data.js/2.4.3/ember-data.js",
    "ember-template-compiler": "https://cdnjs.cloudflare.com/ajax/libs/ember.js/2.4.3/ember-template-compiler.js"
  }
}