title: How to add Custom class on custom button in TinyMCE 4 addButton()
body: <p>I want to add custom class on custom button in tinyMCE addButton() function.</p>
  
  <p>For Example</p>
  
  <pre><code>editor.addButton('keywords', {
                text: 'Insert Keywords',
                class: 'MyCoolBtn', 
                icon: false,
                onclick: function () {
  
                    if($(this.id).hasClass("mce-active"))
                        EditorMethods.removeKeywordsToolbar(this.id);
                    else
                        EditorMethods.displayKeywordsToolbar(this.id);  
                }
            });
  </code></pre>
  
  <p>This does not work for me.
  TinyMCE JS add unique Id and some classes on the div containing the button. I want to add my custom class along with other classes on that div.</p>
  
  <p>Current HTML of button is</p>
  
  <p><div class="snippet" data-lang="js" data-hide="false">
  <div class="snippet-code">
  <pre class="snippet-code-css lang-css prettyprint-override"><code> &lt;div aria-labelledby="mceu_35" tabindex="-1" class="mce-widget mce-btn mce-first mce-last mce-btn-has-text mce-active" id="mceu_35" role="button"&gt; &lt;button tabindex="-1" type="button" role="presentation"&gt; &lt;span class="mce-txt"&gt;Insert Keywords&lt;/span&gt; &lt;/button&gt; &lt;/div&gt;</code></pre>
  </div>
  </div>
  </p>
  
  <p>Please suggest a way to either get the div Id  or to Insert the class on that div containg that button. </p>